Minerals
Dr. Jay Maron

Charts
Mineral classes
Gems
Valence
Oxides
Oxyanions

Abundance
Economic importance
Prospecting
Ancient minerology
Discovery of minerals
Smelting

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Charts

Mineral classes


Density and hardness


Density and metal


Mineral classes

Elemental

Volcanic sulfur
Iron meteorite
Silver
Platinum
Gold


Carbide

Diamond: C


Carbonate

Dolomite: CaMg(CO3)2
Malachite: Cu2CO3(OH)l2
Azurite: Cu3(CO3)2(OH)2
Aragonite: CaCO3
Rhodochrosite: MnCO3

Pearl: CaCO3
Calcite: CaCO3


Oxide

Rutile: TiO2
Pyrolusite: MnO2
Corundum: Al2O3
Rhodonite: MnSiO3
Tourmaline: (Ca,Na,K,)(Li,Mg,Fe+2,Fe+3,Mn+2,Al,Cr+3,V+3)3(Mg,Al,Fe+3,V+3,Cr+3)6((Si,Al,B)6O18)(BO3)3(OH,O)3(OH,F,O)

Opal: SiO2·nH2O
Agate: SiO2

Amethyst: SiO2
Quartz: SiO2
Citrine: SiO2

Hematite: Fe2O3
Hematite: Fe2O3
Zircon: ZrSiO4
Spinel: MgAl2O4

Ruby
Sapphire
Sapphire
Sapphire


Hydroxide

Bauxite: Al(OH)3 and AlO(OH)
Goethite: FeO(OH)


Fluoride

Fluorite: CaF2
Muscovite mica: KAl2(AlSi3O10)(F,OH)2 or KF2(Al2O3)3(SiO2)6(H2O)
Topaz: Al2SiO4(F,OH)2


Silicate

Spodumene: LiAl(SiO3)2
Topaz: Al2SiO4(F,OH)2
Stilbite: LiAlSi2O6
Beryl: Be3Al2(SiO3)6
Epidote: Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)

Garnet: [Mg,Fe,Mn]3Al2(SiO4)3 & Ca3[Cr,Al,Fe]2(SiO4)3
Jadeite: NaAlSi2O6
Albite: NaAlSi3O8
Amazonite: KAlSi3O8
Labradorite: (Na,Ca)(Al,Si)4O8

Emerald: Be3Al2(SiO3)6
Peridot: (Mg,Fe)2SiO4
Morganite: Be3Al2(SiO3)6


Phosphate

Turquoise: CuAl6(PO4)4(OH)8•4(H2O)


Sulfide

Pyrite: FeS2
Chalcopyrite: CuFeS2
Bornite: Cu5FeS4
Sphalerite: ZnS
Galena: PbS


Sulfate

Selenite: CaSO4 · 2H2O
Satin Spar: CaSO4 · 2H2O
Celestine: SrSO4
Barite: BaSO4


Chloride

Halite: NaCl


Gems

Ruby
Diamond
Topaz
Zircon: ZrSiO4
Spinel: MgAl2O4

Sapphire
Sapphire
Sapphire

Emerald
Beryl: Be3Al2(SiO3)6
Morganite

Quartz
Amethyst: SiO2
Amethyst: SiO2
Citrine: SiO2

Garnet: [Mg,Fe,Mn]3Al2(SiO4)3 & Ca3[Cr,Al,Fe]2(SiO4)3
Peridot: (Mg,Fe)2SiO4
Opal: SiO2·nH2O
Jadeite: NaAlSi2O6
Pearl: CaCO3
Amber: Resin

Corundum is a crystalline form of aluminium oxide (Al2O3). It is transparent in its pure form and can have different colors when metal impurities are present.

             Color    Colorant  carat ($)

Painite                          55000  CaZrAl9O15(BO3)
Diamond      Clear                1400  C
Ruby         Red      Chromium   15000  Al2O3
Sapphire     Blue     Iron         650  Al2O3
Sapphire     yellow   Titanium          Al2O3
Sapphire     Orange   Copper            Al2O3
Sapphire     Green    Magnesium         Al2O3
Emerald      Green    Chromium          Be3Al2(SiO3)6
Beryl        Aqua     Iron              Be3Al2(SiO3)6   AKA "aquamarine"
Morganite    Orange   Manganese    300  Be3Al2(SiO3)6
Topaz        Topaz                      Al2SiO4(F,OH)2
Spinel       Red      Red               MgAl2O4
Quartz       Clear                      SiO2
Amethyst     Purple   Iron              SiO2
Citrine      Yellow                     SiO2
Zircon       Red                        ZrSiO4
Garnet       Orange                     [Mg,Fe,Mn]3Al2(SiO4)3 & Ca3[Cr,Al,Fe]2(SiO4)3
Garnet       Blue                 1500  [Mg,Fe,Mn]3Al2(SiO4)3 & Ca3[Cr,Al,Fe]2(SiO4)3
Opal                                    SiO2·nH2O
Opal         Black               11000  SiO2·nH2O
Jet          Black                      Lignite
Peridot      Green                      (Mg,Fe)2SiO4
Pearl        White                      CaCO3
Jade         Green                      NaAlSi2O6
Amber        Orange                     Resin

Crystals
Crystal, polycrystal, and amorphous

Diamond
Carbon phase diagram

Corundum (Al2O3)
Corundum unit cell
Corundum

Metal lattice
Salt (NaCl)
Tungsten Carbide

Alpha quartz (SiO2)
Beta quartz
Glass (SiO2)
Ice


Phosphorescence

                                                 Strength   Decay time

SrOAl2O3   Strontium aluminate     Light green      1          1
ZnS        Zinc sulfide            Dark green        .1         .1
CaS        Calcium sulfide         Red
SrS        Strontium sulfide

We use relative units for strength and decay time


Valence

Hydrogen molecules (hydrides)

LiH
BeH2
BH3
CH4
NH3
H2O
HF

Hydrogen forms molecules with all elements except the noble gases, osmium, iridium, promethium, francium, and radium. This makes it a benchmark for determining the number of bonds that each element forms, as well as the strength of each element's attraction for electrons.


Valence sites

The "valence number" is the number of bonds that an element can form. The valence number for each element can be inferred from the table of hydrides. Elements in the same column of the periodic table have the same valence number. The following table shows the valence number for each column of the periodic table.

   1           2        3          4           3          2          1          0

Hydrogen                                                                      Helium
Lithium    Beryllium  Boron      Carbon     Nitrogen    Oxygen    Fluorine    Neon
Sodium     Magnesium  Aluminum   Silicon    Phosphorus  Sulfur    Chlorine    Argon
Potassium  Calcium    Gallium    Germanium  Arsenic     Selenium  Bromine     Krypton

Valence of metals

The table gives the most common oxidation number for each metal.

Lithium    1              Potassium  1
Beryllium  2              Calcium    2
                          Scandium   3
Sodium     1              Titanium   4
Magnesium  2              Vanadium   4
Aluminum   3              Chromium   4
                          Manganese  4
                          Iron       3
                          Cobalt     2
                          Nickel     2
                          Copper     3
                          Zinc       2

Oxides

Fe2O3  paint

H2O
Li2O
BeO
B2O3
CO2
N2O
O2
OF2

The oxides of copper are:

1 electron:       Cu2O   Copper(I) Oxide.  Cuprous oxide. Red paint
2 electrons:      CuO    Copper(II) Oxide.  Cupric oxide. Black color
3 electrons:      Cu2O3   Copper(III) Oxide
"Electrons" refers to the number of electrons that each copper atom gives to the oxygen atoms.

The oxides of iron are:

3 electons:       Fe2O3  Iron(III) Oxide.  Ferric oxide.  Most common form
2 electrons:      FeO    Iron(II) oxide.  Rare
2 or 3 electrons: Fe3O4  Iron(II,III) Oxide.  Magnetite

In the table, the "e-" column denotes the number of electrons given by the element to oxygen atoms.

        e-

 1  H   1   H2O    Water
 2  He  0          Does not react with oxygen
 3  Li  1   Li2O
 4  Be  2   BeO    Beryllium oxide
 5  B   3   B2O3   Boron trioxide. Most common form.  High conductivity
       1/3  B6O    Boron suboxide.  High conductivity and hardness
 6  C   4   CO2    Carbon dioxide
        2   CO     Carbon monoxide.  Toxic.  Displaces oxygen from hemoglobin
 7  N   1   N2O    Nitrous oxide.  Laughing gas
        2   NO     Nitric oxide.  Gas.  Signaling molecule.  Decomposes in air to NO2
        4   NO2    Nitrogen dioxide.  Toxic gas
        4   N2O4   Dinitrogen tetroxide
        5   N2O5   Dinitrogen pentoxide
 8  O       O2     Oxygen
            O3     Ozone
 9  F  -2   OF2    Oxygen difluoride
10  Ne  0          Does not react with oxygen
11  Na  1   Na2O   Sodium oxide
12  Mg  2   MgO    Magnesium oxide
13  Al  3   Al2O3  Aluminum(III) oxide. Aluminum oxide. Most common form
        2   AlO    Aluminum(II) oxide. Aluminum monoxide
        1   Al2O   Aluminum(I) oxide
14  Si  4   SiO2   Quartz
15  P   4   P2O4   Diphosphorus tetroxide
        3   P4O6   Phosphorus trioxide.  Phosphorus(III) oxide. Stable. Reacts with water
        5   P4O10  Phosphorus pentoxide
16  S   6   SO3    Sulfur trioxide.  Component of acid rain
        4   SO2    Sulfur dioxide.  Toxic gas
        2   SO     Sulfur monoxide.  Unstable
17  Cl  4   ClO2   chlorine dioxide
        2   ClO    Foe of the ozone layer
        1   Cl2O   Dichlorine monoxide. Unstable. Explosive
18  Ar  0          Does not react with oxygen
19  K   1   K2O    Potassium oxide
20  Ca  2   CaO    Calcium oxide   Quicklime
21  Sc  3   Sc2O3  Scandium(III) oxide.  Ceramic
22  Ti  4   TiO2   Titanium dioxide.  Most common form
        3   Ti2O3  Dititanium trioxide
        2   TiO    Titanium monoxide.  Corundum structure.  Tistarite ore (extremely rare)
23  V   5   V2O5   Vanadium(V) oxide. Rare mineral
        4   VO2    Vanadium(IV) oxide
        3   V2O3   Vanadium(III) oxide. Morphs in air to V2O4
        2   VO     Vanadium(II) oxide
24  Cr  2   CrO    Chromium(II) oxide
        3   Cr2O3  Chromium(III) oxide.  Eskolaite ore
        4   CrO2   Chromium dioxide
        6   CrO3   Chromium trioxide
25  Mn  7   Mn2O7  Manganese(VII) oxide.  Extremely unstable
        6   MnO3   Manganese(VI) oxide
        4   MnO2   Manganese dioxide.  Most common form
        3   Mn2O3  Manganese(III) oxide
       8/3  Mn3O4  Manganese(II,III) oxide
        2   MnO    Manganese(II) oxide.  Rare mineral
26  Fe  3   Fe2O3  Iron(III) Oxide.  Ferric oxide.  Most common form
        2   FeO    Iron(II) oxide.  Rare
       8/3  Fe3O4  Iron(II,III) Oxide.  Magnetite
27  Co  3   Co2O3  Cobalt(II) oxide.  Cobaltic oxide
        2   CoO    Cobalt(II) oxide.  Cobaltous oxide
       8/3  Co3O4  Cobalt(II,IIIs) oxide.  Cobaltous oxide
28  Ni  2   NiO    Nickel(II) oxide
29  Cu  1   Cu2O   Copper(I) Oxide.  Cuprous oxide. Red paint
        2   CuO    Copper(II) Oxide.  Cupric oxide. Black color. Common ore
        3   Cu2O3  Copper(III) Oxide
30  Zn  2   ZnO    Zinc oxide
30  Ga  1   GaO2   Gallium(I) oxide
    Ga  3   Ga2O3  Gallium(III) oxide
32  Ge  2   GeO2   Germanum oxide

Oxyanions

Water
Carbonic acid
Nitric acid
Nitrous acid
Silicic acid
Phosphoric acid
Sulfuric acid

Hydroxide
Carbonate
Nitrate
Nitrite
Silicate
Phosphate
Sulfate

Type         Example

Hydroxide    HOH          Hydrogen hydroxide
Hypofluorite HFO          Hypoflourous acid
Hypochlorite HClO         Hypochlorous acid

Peroxide     H2O2         Hydrogen peroxide

Carbide      WC           Tungsten carbide
Oxide        H2O          Hydrogen oxide
Fluoride     HF           Hydrogen fluoride
Silicide     H4Si         Hydrogen silicide
Phosphide    H3P          Hydrogen phosphide
Sulfide      H2S          Hydrogen sulfide
Chloride     HCl          Hydrogen chloride
Arsenide     H3As         Hydrogen arsenide
Selenide     H2Se         Hydrogen selenide
Bromide      HBr          Hydrogen bromide

Carbonate    H2CO3        Carbonic acid
Nitrate      HNO3         Nitric acid
Aluminate    H5AlO4       Hydrogen aluminate
Silicate     H4SiO4       Silicic acid
Phosphate    H3PO4        Phosphoric acid
Sulfate      H2SO4        Sulfuric acid
Chlorate     HClO3        Hydrogen chlorate
Perchlorate  HClO4        Hydrogen perchlorate
Germanate    H4GeO4       Hydrogen germanate
Arsenate     H3AsO4       Arsenic acid
Selenate     H2SeO4       Hydrogen selenate
Bromate      HBrO3        Hydrogen bromate
Tellurate    H2TeO4       Hydrogen tellurate
Iodate       HIO3         Hydrogen iodate

Nitrite      HNO2         Nitrous acid
Chlorite     HClO2        Hydrogen chlorite

Carbides

Tungsten carbide drill
Tungsten carbide
Silicon carbide
Boron carbide

      Carbon atoms per metal atom

Boron      1/4
Silicon     1
Titanium    1
Beryllium  1/2
Zirconium  1/2
Tantalum    1
Tungsten    1
Aluminum   3/4

Electronegativity

Every atom attracts electrons and the electronegativity table shows the relative energy released when the atom captures an electron. The elements in the upper right are the most electron-hungry.

In the reaction   H + H + O   →   H2O,   The oxygen steals an electron from each of the two hydrogens. It is able to do this because the electrons are at a lower energy with oxygen than with hydrogen.

Most chemical reactions involve elements on the left side of the periodic table giving electrons to elements on the right side.


Hydrogen bond energy

The table gives the energy to remove a hydrogen from a hydride molecule. This is the data used to construct the electronegativity table.

Element  Molecule   Bond energy
                        (eV)

  H      H2       4.52
  Li     LiH      2.56
  Be     BeH2     2.35
  B      BH3      3.43
  C      CH4      3.52
  N      NH3      3.26
  O      H2O      4.41
  F      HF       4.90
  Na     NaH      2.09
  Mg     MgH2     2.04
  Al     AlH3     2.96
  Si     SiH4     3.10
  P      PH3      3.56
  S      H2S      3.57
  Cl     HCl      4.48
  K      KH       1.90
  Ca     CaH2     1.74
  Ga               ?
  Ge              3.36
  As              2.82
  Se     SeH2     3.17
  Br     HBr      3.80

Abundance

 Siderophile:  Iron-living. Tends to sink to the core along with iron.
 Lithophile:   Rock-loving. Tends to become included in rock and escapes sinking to the core.
 Chalcophile:  Ore-loving. Tends to combine with oxygen and sulfur and escapes sinking to the core.
 Atmophile:    Is a gas at room temperature and tends to escape the crust into the atmosphere.

The abundance of elements in the Earth's crust is:

A metal asteroid is a representation of the Earth's core. Platinum group metals and dense metals tend to sink to the core.

Tungsten is dense but escapes sinking to the core by mineralizing. This is why tungsten is cheap and all other dense metals are expensive.


Core amplification

The core concentrates iron and other siderophiles. The concentration of iron is larger in the core than in the crust.

The chart shows the degree to which the core concentrates elements, with iron normalized to "1".

Platinum is more dense than iron and is hence more likely to sink to the Earth's core than iron. This is reflected in the "core amplification factor".

Platinum abundance in the crust =  cPt  =      .004 ppm
Iron abundance in the crust     =  cFe  = 63000     ppm
Platinum abundance in the core  =  CPt  =    19     ppm
Iron abundance in the core      =  CFe  =910000     ppm
Crust platinum/iron             =  cPt/cFe  =  .000000063
Core  platinum/iron             =  CPt/CFe  =  .000021
Core amplification factor       =  APt  =  (CPt/CFe) / (cPtcFe)  =  329

Economic impact

Element price


Applications

For most minerals, the economic importance is the metal it contains.

            Chief ore     Chief uses

Lithium     Spodumene     Lithium-ion batteries              LiAl(SiO3)2
            Lepidolite                                       K(Li,Al)3(Si,Al)4O10(F,OH)2
Beryllium   Beryl         Lightweight metal, copper alloy    Be3Al2(SiO3)6
Boron       Ulexite       Glass, ceramics, fiberglass        NaCa[B5O6(OH)6]·5H2O
            Colemanite                                       Ca2B6O11·5H2O
            Kernite                                          Na2B4O6(OH)2·3H2O
            Tincal                                           Na2B4O7·10H2O
Fluorine    Fluorite      UF6, organofluorides, circuit breakers  CaF2
Magnesium   Periclase     Al alloy, die-asting, Fe smelting  MgO
            Magnesite                                        MgCO3
            Dolomite                                         CaMg(CO3)2
Aluminum    Bauxite       Structural metal                   Al(OH)3, AlO(OH)
Phosphorus  Phosphate rock   Fertilizer
Potassium   Brine         Fertilizer
Scandium    Thortvetite   Aluminum alloy                     (Sc,Y)2Si2O7
Titanium    Rutile        Pigments, alloys, aircraft         TiO2
Vanadium    Vanadinite    Steel alloy                        Pb5(VO4)3Cl
Chromium    Chromite      Steel alloy                        FeCr2O4
Manganese   Pyrolusite    Steel alloy, Aluminum alloy        MnO2
            Braunite                                         Mn+2Mn+36)SiO12
            Psilomelane                                      (Ba,H2O)2Mn5O10
            Rhodochrosite                                    MnCO3
Iron        Hematite      Structural metal                   Fe2O3
Cobalt      Cobaltite     Li-ion batteries, steel alloy      CoAsS
Nickel      Millerite     Steel alloy                        NiS
            Nickeline                                        NiAs
Copper      Chalcocite    Conductors                         Cu2S
Zinc        Sphalerite    Brass                              ZnS
            Smithsonite                                      ZnCO3
            Hemimorphite                                     Zn4(Si2O7)(OH)2·H2O
Gallium     Aluminum ore  Semiconductors                     Al(OH)3 and AlO(OH)
Germanium   Germanite     Fiber optics                       Cu26Fe4Ge4S32
Arsenic     Realgar       Pesticides                         As4S4
            Arsenopyrite                                     FeAsS
Selenium    Chalcocite    Glass, Bi & Brass alloy            Cu2S
Bromine     Brine         Flame retardant, organobromides
Rubidium    Lepidolite    Fireworks                          K(Li,Al)3(Si,Al)4O10(F,OH)2
Strontium   Celestite     Cathode ray tubes, fireworks       SrSO4
Yttrium     Rare-earth ore  CRTs
Zirconium   Zircon        Nuclear reactors                   ZrSiO4
Niobium     Niobite       Steel alloy, superalloy, superconductors
Molybdenum  Molybdenite   Steel alloy                        MoS2
Ruthenium   Nickel ore    Electrical contacts, catalysts
Rhodium     Nickel ore    Catalyst
Palladium   Nickel ore    Catalyst
Silver      Acanthite     Currency, conductors               Ag2S
            Argentite
Cadmium     Zinc ore      Batteries, pigments, electroplating
            Greenockite                                      CdS
Indium      Cu & Zn ore   LCDs, semiconductors, solder       Sphalerite and chalcopyrite
Tin         Cassiterite   Bronze and solder                  SnO2
Antimony    Stibnite      Flame retardant, Pb alloy          Sb2S3
Tellurium   Chalcocite    Fe, Cu, Pb alloy                   Cu2S
Iodine      Brine         Organoiodides                      Ca(IO3)2
            Lautarite                                        Ca(IO3)2
            Dietzeite                                        7Ca(IO3)2·8CaCrO4
Caesium     Pollucite     Drill fluid                        (Cs,Na)2Al2Si4O12·2H2O
Barium      Barite        Drill fluid, CRTs, pigments        BaSO4
Rare-earths Mozanite      Electronics, solar cells, magnets  (Nd,La,Ce)PO4
Hafnium     Titanium ore  Fission control rods, High-T materials  ZrSiO4
Tantalum    Tantalite     Steel alloy, capacitors, high-T materials  (Fe,Mn)Ta2O6
Tungsten    Wolframite    Carbides, alloys                   FeWO4
            Scheelite                                        CaWO4
Rhenium     Moly ore      Aircraft turbines
Osmium      Platinum ore  Pens, electrical contacts
Iridium     Platinum ore  Crucibles, spark plugs
Platinum    Sperrylite    Catalyst                           PtAs2
Gold        Native metal  Currency, jewelry, electronics
Mercury     Cinnabar      Chem industry, electronics         HgS
Thallium    Chalcocite    Infrared detectors                 Cu2S
            Lorandite                                        TlAsS2
            Crookesite                                       Cu7(Tl,Ag)Se4
Lead        Galena        Batteries                          PbS
            Anglesite                                        PbSO4
            Cerussite                                        PbCO3
Bismuth     Bismite       Lead replacement, alloys           Bi2O3
            Bismuthinate                                     Bi2S3
Thorium     Rare-earth ore  Lightbulb filaments, nuclear power
Uranium     Uranite       Nuclear power                      UO2

The metals from manganese to zinc can be extracted by smelting with carbon. The metals from potassium to vanadium can't be extracted by smelting and instead require electrolysis.

Many elements are obtained as byproducts from other elements. For example, gallium is a byproduct of aluminum extraction.


Ore

Element price tends to be inversely proportional to the concentration of the element in ore. Miners search for good ore, ore that has a high concentration of the target element.

Rare elements tend to be valuable.

"Embodied energy" is the energy/kg required to extract an element. It's proportional to price and inversely proportional to ore concentration.


Prospecting and mineral density

The more dense the metal, the more valuable it tends to be, hence dense minerals tend to be valuable. Prospectors look for dense minerals.

The densest metals are often mineralized with arsenic, antimony, or tellurium, which further increases the density of the mineral.

All minerals with a density larger than 4 grams/cm3 have valuable metals.

Almost all metals beyond calcium in the periodic table are valuable.

In the world of mineralogy, a Holy Grail is to discover a new mineral, because it gets named after you. If you want to discover a new mineral, you must know all known minerals. The same principle applies to bird ID, tree ID, flower ID, insect ID, etc.

The abundance of an element in the Earth's crust is reflected in the amount the element is mined per year.

For an element to be useful as currency, it should be toward the right of the plot, and toward the bottom, and it should have industrial importance.

The best mines for platinum-group metals are metal asteroid craters. Metal asteroids are 90% iron, 10% nickel, and rich in platinum-group elements. These mines are rich in nickel ore, and platinum-group minerals tend to accompany nickel minerals. Many platinum-group metals are a byproduct of nickel extraction.

The best metal asteroid mines are Sudbury Canada, and Vredefort South Africa.

Platinum-group metals tend to mineralize with sulfur, tellurium, arsenic, and antimony. Metal asteroid mines are rich sources of these mineral classes.


Dense liquids

Minerals can be isolated from rock with dense liquids. Rock has a density between 2.7 and 3.3 gram/cm3, hence anything more dense than this is a mineral. Almost all minerals with a density larger than 3.3 grams/cm3 have valuable elements. In ancient times, gold was mined with mercury. The dense liquids are:

              Density    Melt     Boil    Price/Mass
              gram/cm3  Celsius  Celsius     $/kg

Mercury          13.53    -39     357        50
Lead             11.34    327    1749         2.1
BiPbSnCdInTl     10        42                37      Bi=40.3 Pb=22.2 Sn10.7 In17.7  Cd8.1 Tl=1.1
Bismuth           9.78    272    1564         6
Field's metal     8.1      62                97      Bi=32.5%, Sn=16.5%, In=51%
Indium            7.31    157    2072       180
Gallinstan        6.44    -19               208      68.5% Ga, 21.5% In, and 10.0% Sn.   Non-toxic
Gallium           5.91     30    2400       245
Caesium formate   2.3    1749             50000      Cs(HCOO)     Drilling lubricant

        Price ($/kg)

Lead          2.1
Cadmium       2.7
Bismuth       6
Tin          18
Mercury      50
Tellurium    71
Indium      180
Gallium     245
Caesium   62000

Ancient metallurgy

Stone
Copper
Bronze
Iron
Carbon

Gold and silver were known since antiquity because they occur naturally in pure form. Gold mining started in 6000 BCE and silver smelting started in 4000 BCE.

Iron can occasionally be found as iron meteorites.

Gold nugget
Silver nugget
Iron meteorite

Copper was discovered around 7500 BCE by smelting copper minerals in a wood fire. Around 3200 BCE it was found that copper is strenghened by tin, and this is bronze. Around 2000 BCE it was found that copper is also strengthed by zinc, and this is brass.

The earliest metals were smeltable with a wood fire and they consist of copper, lead, silver, tin, zinc, and mercury. They come from the following minerals:

Lead. Galena. PbS
Copper. Chalcocite. Cu2S
Silver. Acanthite. Ag2S
Tin. Cassiterite. SnO2
Zinc. Sphalerite. ZnS
Mercury. Cinnabar. HgS

The next metal to be discovered was iron (c. 1200 BC), which requires a bellows-fed coal fire to smelt.

Iron. Hematite. Fe2O3
Iron. Pyrite. FeS2

No new metals were discovered until cobalt in 1735. Once cobalt was discovered, it was realized that new minerals may have new metals, and the race was on to find new minerals. This gave nickel, chromium, manganese, molybdenum, and tungsten.

Cobalt. Cobaltite. CoAsS
Nickel. Millerite. NiS
Chromium. Chromite. FeCr2O4
Manganese. Pyrolusite. MnO2
Molybdenum. Molybdenite. MoS2
Tungsten. Wolframite. FeWO4

Chromium is lighter and stronger than steel and was discovered in 1797. It satisfies the properties of mithril from "Lord of the Rings" and Valyrian steel from "Game of Thrones". There's no reason chromium couldn't have been discovered earlier.

Coal smelting can't produce the metals lighter than chromium. These need electrolysis. The battery was invented in 1799, enabling electrolysis, and the lighter metals were discovered shortly after. These include aluminum, magnesium, titanium, and beryllium. Once you have

Aluminum. Bauxite. Al(OH)3 and AlO(OH)
Mangesium. Magnesite. MgCO3
Titanium. Rutile. TiO2
Beryllium. Beryl. Be3Al2(SiO3)6

Carbon fiber eclipses metals. The present age could be called the carbon age. The carbon age became mature in 1987 when Jimmy Connors switched from a wood to a carbon racket.

The plot shows the strength of materials.

Alloys can be much stronger than pure metals.

Wood rivals alloys for strength.


Currency

Gold was the densest element known until the discovery of platinun in 1735. It was useful as an uncounterfeitable currency until the discovery of tungsten in 1783, which has the same density as gold. Today, we could use iridium, platinum, or rhenium as an uncounterfeitable currency.


Modern chemistry and the discovery of elements

Prior to 1800, metals were obtained by smelting minerals, and the known metals were gold, silver, copper, iron, tin, zinc, mercury, cobalt, manganese, chromium, molybdenum, and tungsten. Elements to the left of chromium titanium and scandium cant's be obtained by smelting, and neither can aluminum, magnesium, and beryllium. They require electrolysis, which was enabled by Volta's invention of the battery in 1799.

Prior to 1800, few elements were known in pure form. Electrolyis enabled the isolation of most of the rest of the elements. The periodic table then became obvious and was discovered by Mendeleev 1871. The battery launched modern chemistry, and the battery could potentially have been invented much earlier.

Electrolysis enabled the isolation of sodium and potassium in 1807, and these were used to smelt metals that can't be smelted with carbon.

         Discovery   Method of             Source
          (year)     discovery

Carbon     Ancient   Naturally occuring
Gold       Ancient   Naturally occuring
Silver     Ancient   Naturally occuring
Sulfur     Ancient   Naturally occuring
Lead         -6500   Smelt with carbon     Galena       PbS
Copper       -5000   Smelt with carbon     Chalcocite   Cu2S
Bronze (As)  -4200   Copper + Arsenic      Realgar      As4S4
Tin          -3200   Smelt with carbon     Calamine     ZnCO3
Bronze (Sn)  -3200   Copper + Tin
Brass        -2000   Copper + Zinc         Sphalerite   ZnS
Mercury      -2000   Heat the sulfide      Cinnabar     HgS
Iron         -1200   Smelt with carbon     Hematite     Fe2O3
Arsenic       1250   Heat the sulfide      Orpiment     As2S3
Zinc          1300   Smelt with wool       Calamine     ZnCO3 (smithsonite) & Zn4Si2O7(OH)2·H2O (hemimorphite)
Antimony      1540   Smelt with iron       Stibnite     Sb2S3
Phosphorus    1669   Heat NaPO3 Excrement
Cobalt        1735   Smelt with carbon     Cobaltite    CoAsS
Platinum      1735   Naturally occuring
Nickel        1751   Smelt with carbon     Nickeline    NiAs
Bismuth       1753   Isolated from lead
Hydrogen      1766   Hot iron + steam      Water
Oxygen        1771   Heat HgO
Nitrogen      1772   Isolated from air
Manganese     1774   Smelt with carbon     Pyrolusite   MnO2
Molybdenum    1781   Smelt with carbon     Molybdenite  MoS2
Tungsten      1783   Smelt with carbon     Wolframite   (Fe,Mn)WO4
Chromium      1797   Smelt with carbon     Crocoite     PbCrO4
Palladium     1802   Isolated from Pt
Osmium        1803   Isolated from Pt
Iridium       1803   Isolated from Pt
Rhodium       1804   Isolated from Pt
Sodium        1807   Electrolysis
Potassium     1807   Electrolysis
Magnesium     1808   Electrolysis          Magnesia     MgCO3
Cadmium       1817   Isolated from zinc
Lithium       1821   Electrolysis of LiO2  Petalite     LiAlSi4O10
Zirconium     1824   Smelt with potassium  Zircon       ZrSiO4
Aluminum      1827   Smelt with potassium
Silicon       1823   Smelt with potassium
Beryllium     1828   Smelt with potassium  Beryl        Be3Al2Si6O18
Thorium       1929   Smelt with potassium  Gadolinite   (Ce,La,Nd,Y)2FeBe2Si2O10
Vanadium      1831   Smelt VCl2 with H2    Vanadinite   Pb5(VO4)3Cl
Uranium       1841   Smelt with potassium  Uranite      UO2
Ruthenium     1844   Isolated from Pt
Tantalum      1864   Smelt with hydrogen   Tantalite    [(Fe,Mn)Ta2O6]
Niobium       1864   Smelt with hydrogen   Tantalite    [(Fe,Mn)Ta2O6]
Fluorine      1886   Electrolysis
Helium        1895   From uranium ore
Titanium      1910   Smelt with sodium     Ilmenite     FeTiO3
Hafnium       1924   Isolated from zirconium
Rhenium       1928   Isolated from Pt
Scandium      1937   Electrolysis          Gadolinite   FeTiO3

History of mineralogy

 -384  -322   Aristotle. Wrote "Meteorology"
 -370  -285   Theophrastus. Wrote "De Mineralibus"
         77   Pliny the Elder publishes "Natural History"
  973  1050   Al Biruni. Published "Gems"
       1546   Georgius Agricola publishes "On the Nature of Rocks"
       1556   Georgius Agricola publishes "On Metals"
       1609   de Boodt publishes a catalog of minerals
       1669   Brand: Discovery of phosphorus
       1714   John Woodward publishes "Naturalis historia telluris illustrata & aucta", a mineral catalog
       1735   Brandt: Discovery of cobalt
       1777   Lavoisier: Discovery of sulfur
       1778   Lavoisier: Discovery of oxygen and prediction of silicon
       1783   Lavoisier: Discovery of hydrogen
       1784   T. Olof Bergman publishes "Manuel du mineralogiste, ou sciagraphie du regne mineral",
              and founds analytical chemistry
       1778   Lavoisier: Discovery of oxygen
       1801   Rene Just Huay publishes "Traite de Mineralogie", founding crystallography
       1811   Avogadro publishes "Avogadro's law"
       1860   The Karlsruhe Congress publishes a table of atomic weights
       1869   Mendeleev publishes the periodic table

Appendix

Minerals

These elements are not necessarily on the Science Olympiad list.

We list minerals by element, with the most abundant mineral for each element listed first.

Lithium

Spodumene: LiAl(SiO3)2
Stilbite: LiAlSi2O6
Tourmaline: (Ca,Na,K,)(Li,Mg,Fe+2,Fe+3,Mn+2,Al,Cr+3,V+3)3(Mg,Al,Fe+3,V+3,Cr+3)6((Si,Al,B)6O18)(BO3)3(OH,O)3(OH,F,O)

Beryllium

Beryl: Be3Al2(SiO3)6
Morganite: Be3Al2(SiO3)6
Emerald

Carbon

Diamond: C

Sodium

Halite: NaCl

Magnesium

Periclase: MgO
Magnesite: MgCO3
Dolomite: CaMg(CO3)2
Peridot: (Mg,Fe)2SiO4
Spinel: MgAl2O4
Spinel: MgAl2O4

Aluminum

Bauxite: Al(OH)3 and AlO(OH)
Alumstone: KAl3(SO4)2(OH)6
Muscovite mica: KAl2(AlSi3O10)(F,OH)2 or KF2(Al2O3)3(SiO2)6(H2O)
Corundum: Al2O3
Topaz: Al2SiO4(F,OH)2

Epidote: Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)
Jadeite: NaAlSi2O6
Albite: NaAlSi3O8
Amazonite: KAlSi3O8
Labradorite: (Na,Ca)(Al,Si)4O8

Silicon

Amethyst: SiO2
Quartz: SiO2
Citrine: SiO2
Opal: SiO2·nH2O
Agate: SiO2

Sulfur

Volcanic sulfur

Calcium

Fluorite: CaF2
Calcite: CaCO3
Satin Spar: CaSO4 · 2H2O
Selenite: CaSO4 · 2H2O
Aragonite: CaCO3
Pearl: CaCO3
Calcite: CaCO3

Titanium, vanadium, chomium, and manganese

Rutile: TiO2
Vanadinite: Pb5(VO4)3Cl
Chromite: FeCr2O4
Pyrolusite: MnO2
Rhodonite: MnSiO3
Rhodochrosite: MnCO3

Iron

Hematite: Fe2O3
Hematite: Fe2O3
Pyrite: FeS2
Iron meteorite
Goethite: FeO(OH)

Cobalt and nickel

Cobaltite: CoAsS
Millerite: NiS

Copper

Chalcocite: Cu2S
Chalcopyrite: CuFeS2
Malachite: Cu2CO3(OH)l2
Azurite: Cu3(CO3)2(OH)2
Bornite: Cu5FeS4
Turquoise: CuAl6(PO4)4(OH)8•4(H2O)

Zinc and germanium

Sphalerite: ZnS
Germanite: Cu26Fe4Ge4S32

Strontium, zirconium, molybdenum

Celestine: SrSO4
Strontianite: SrCO3
Zircon: ZrSiO4
Molybdenite: MoS2

Silver

Argentite: Ag2S
Acanthite: Ag2S
Silver nugget

Tin

Cassiterite: SnO2

Caesium, barium, rare-earths

Pollucite: (Cs,Na)2Al2Si4O12·2H2O
Barite: BaSO4
Monazite: (Ce,La,Nd,Th)PO4

Tungsten

Wolframite: FeWO4
Scheelite: WCaO4
Hubnerite: WMnO4

Platinum, gold, mercury, lead

Sperrylite: PtAs2
Platinum nugget
Gold nugget
Cinnabar: HgS
Galena: PbS
Anglesite: PbSO4
Thorite: (Th,U)SiO4


Charts

Density and metal


Mineral classes


Density and hardness


Metal smelting

Prehistoric-style smelter

Most metals are in oxidized form. The only metals that can be found in pure form are gold, silver, copper, platinum, palladium, osmium, and iridium.

Smelting is a process for removing the oxygen to produce pure metal. The ore is heated in a coal furnace and the carbon seizes the oxygen from the metal. For copper,

Cu2O + C  →  2 Cu + CO
At low temperature copper stays in the form of Cu2O and at high temperature it gives the oxygen to carbon and becomes pure copper.

For iron, the oxidation state is reduced in 3 stages until the pure iron is left behind.

3 Fe2O3 + C  →  2 Fe3O4 + CO
Fe3O4   + C  →  3 FeO   + CO
FeO     + C  →    Fe   + CO
Oxidation state  =  Number of electrons each iron atom gives to oxygen

       Oxidation state
CuO          2
Cu2O         1
Cu           0
Fe2O3        3
Fe3O4       8/3
FeO          2
Fe           0

Smelting temperature

The following table gives the temperature required to smelt each element with carbon.

        Smelt  Method  Year  Abundance
         (C)                   (ppm)

Gold        <0   *   Ancient      .0031
Silver      <0   *   Ancient      .08
Platinum    <0   *    1735        .0037
Mercury     <0  heat -2000        .067
Palladium   <0  chem  1802        .0063
Copper      80   C   -5000      68
Sulfur     200   *   Ancient   420
Lead       350   C   -6500      10
Nickel     500   C    1751      90
Cadmium    500   C    1817        .15
Cobalt     525   ?    1735      30
Tin        725   C   -3200       2.2
Iron       750   C   -1000   63000
Phosphorus 750  heat  1669   10000
Tungsten   850   C    1783    1100
Potassium  850   e-   1807   15000
Zinc       975   C    1746      79
Sodium    1000   e-   1807   23000
Chromium  1250   C    1797     140
Niobium   1300   H    1864      17
Manganese 1450   C    1774    1120
Vanadium  1550   ?    1831     190
Silicon   1575   K    1823  270000
Titanium  1650   Na   1910   66000
Magnesium 1875   e-   1808   29000
Lithium   1900   e-   1821      17
Aluminum  2000   K    1827   82000
Uranium   2000   K    1841       1.8
Beryllium 2350   K    1828       1.9

Smelt:      Temperature required to smelt with carbon
Method:     Method used to purify the metal when it was first discovered
            *:  The element occurs in its pure form naturally
            C:  Smelt with carbon
            K:  Smelt with potassium
            Na: Smelt with sodium
            H:  Smelt with hydrogen
            e-: Electrolysis
            heat:  Heat causes the oxide to decompose into pure metal. No carbon required.
            chem:  Chemical separation
Discovery:  Year the element was first obtained in pure form
Abundance:  Abundance in the Earth's crust in parts per million
Elements with a low carbon smelting temperature were discovered in ancient times unless the element was rare. Cobalt was discovered in 1735, the first new metal since antiquity, and this inspired scientists to smelt every known mineral in the hope that it would yield a new metal. By 1800 all the rare elements that were carbon smeltable were discovered.

The farther to the right on the periodic table, the lower the smelting temperature, a consequence of "electronegativity".

The battery was invented in 1800, launching the field of electrochemistry and enabling the the isolation of non-carbon-smeltable elements. Davy used electrolysis in 1807 to isolate sodium and potassium and then he used these metals to smelt other metals. To smelt beryllium with potassium, BeO + 2 K ↔ Be + K2O.

Titanium can't be carbon smelted because it forms the carbide Ti3C.

Data

For an expanded discussion of smelting physics, see jaymaron.com/metallurgy.html.


Thermite

Thermite is smelting with aluminum. For example, to smelt iron with aluminum,

Fe2O3 + 2 Al  →  2 Fe + Al2O3

Smelting reactions

The following table shows reactions that change the oxidation state of a metal. "M" stands for an arbitrary metal and the magnitudes are scaled to one mole of O2. The last two columns give the oxidation state of the metal on the left and right side of the reaction. An oxidation state of "0" is the pure metal and "M2O" has an oxidation state of "1".

                            Oxidation state   Oxidation state
                                at left          at right
 2  M2O   ↔  4  M     + O2        1                0
 4  MO    ↔  2  M2O   + O2        2                1
 2  M3O4  ↔  6  MO    + O2       8/3               2
 6  M2O3  ↔  4  M3O4  + O2        3               8/3
 2  M2O3  ↔  4  MO    + O2        3                2
 2  MO    ↔  2  M     + O2        2                0
2/3 M2O3  ↔ 4/3 M     + O2        3                0
 1  MO2   ↔  1  M     + O2        4                0
 2  MO2   ↔  2  MO    + O2        4                2