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<!-- mineral data Copyright and courtesy of Geology Park LLC and theGeoZone.com -->

<MineralDatabase>



  <Mineral>

    <Name>AUGITE</Name>

    <DiscreditedNames/>

    <Formula>(Ca,Na)(Mg,Fe,Al)(Si,Al)2O6</Formula>

    <CrystalSystem>monoclinic</CrystalSystem>

    <Hardness>5 - 6</Hardness>

    <SpecificGravity>3.2 - 3.4</SpecificGravity>

    <Luster>vitreous</Luster>

    <Cleavage>imperfect 90º; prismatic {110}</Cleavage>

    <Color>black</Color>

    <Habit>stubby prismatic crystals</Habit>

    <Twinning>twinning on {100} and {001}</Twinning>

    <Tenacity>brittle</Tenacity>

    <Streak>greenish-gray</Streak>

    <Pyrognostics>fuses quietly and with difficulty at 4, producing a shiny dark green to black glass nodule when fused on a charcoal plate; (the globule is magnetic when iron-rich); insoluble in acids (except for titanium-rich varieties which decompose in hot HCl)</Pyrognostics>

    <Birefringence>0.026</Birefringence>

    <Optical2v>25º; - 83º;</Optical2v>

    <RefractionIndices>a = 1.662-1.735 ß = 1.670-1.741 y = 1.688-1.761</RefractionIndices>

    <OpticalProperties>inclined extinction</OpticalProperties>

    <InterferenceFigure>biaxial (+)</InterferenceFigure>

    <Occurrence>found in intermediate, basic, and ultrabasic igneous rocks</Occurrence>

    <Location>fine crystals found in Greenland; Italy; Bushveld Complex, South Africa; Stillwater Complex, Montana</Location>

    <Properties>shows high relief and green to olive-green color in thin section</Properties>

    <Abundance>very common</Abundance>

    <Miscellaneous>titanium-rich varieties show strong pleochroism, beautiful violet color, and zoned "hourglass" structure</Miscellaneous>

    <ChemicalClass>

      <Dana>

        <Class/>

        <Member/>

      </Dana>

      <Strunz>

        <Class/>

        <Member/>

      </Strunz>

    </ChemicalClass>

  </Mineral>



  <Mineral>

    <Name>GOLD</Name>

    <DiscreditedNames/>

    <Formula>Au</Formula>

    <CrystalSystem>isometric</CrystalSystem>

    <Hardness>2½ - 3</Hardness>

    <SpecificGravity>15.0 - 19.3</SpecificGravity>

    <Luster>metallic</Luster>

    <Cleavage>hackly fracture</Cleavage>

    <Color>various shades of yellow</Color>

    <Habit>rare octahedral crystals, arborescent, filiform, dendritic, reticulated</Habit>

    <Twinning>twinning on {111}</Twinning>

    <Tenacity>sectile, ductile, malleable, flexible, inelastic</Tenacity>

    <Streak>yellow</Streak>

    <Pyrognostics>soluble only in aqua regia; fuses easily at 3; impervious to any flux</Pyrognostics>

    <Birefringence>none</Birefringence>

    <Optical2v>none</Optical2v>

    <RefractionIndices>none</RefractionIndices>

    <OpticalProperties>very high reflectivity: R = 74%</OpticalProperties>

    <InterferenceFigure>opaque</InterferenceFigure>

    <Occurrence>hydrothermal veins associated with silicic igneous rocks; also found in alluvial deposits</Occurrence>

    <Location>South Africa; Russia; Canada; Australia; Ghana; California; South Dakota; Nevada; Arizona; Alaska; Utah; Colorado</Location>

    <Properties>very thin sheets transmit a feeble greenish light</Properties>

    <Abundance>very rare</Abundance>

    <Miscellaneous>excellent conductor of heat and electricity</Miscellaneous>

    <ChemicalClass>

      <Dana>

        <Class>Native Elements</Class>

        <Member>1.1.1.1</Member>

      </Dana>

      <Strunz>

        <Class>Elements</Class>

        <Member>I/A.01-40</Member>

      </Strunz>

    </ChemicalClass>

  </Mineral>



  <Mineral>

    <Name>SYLVANITE</Name>

    <DiscreditedNames/>

    <Formula>(Au,Ag)Te2</Formula>

    <CrystalSystem>monoclinic</CrystalSystem>

    <Hardness>1½ - 2</Hardness>

    <SpecificGravity>8.0 - 8.2</SpecificGravity>

    <Luster>brilliant metallic</Luster>

    <Cleavage>perfect {010}</Cleavage>

    <Color>silvery-white</Color>

    <Habit>bladed crystals, also granular masses, forms skeletal or cuneiform-like intergrowths</Habit>

    <Twinning>twinning on {110} which produces distinctive skeletal crystal groups</Twinning>

    <Tenacity>brittle, but thin shavings are sectile</Tenacity>

    <Streak>gray</Streak>

    <Pyrognostics>soluble in HNO3, leaving behind a rusty yellow residue (Au); dissolves in hot, concentrated H2SO4, producing a dark reddish-violet solution (Te); fuses extremely easily at 1; fusion of a mixture of powdered mineral and sodium carbonate flux on a charcoal plate yields a small globule of gold (or electrum if the silver content is high enough) and gives a bluish-green flame (Te)</Pyrognostics>

    <Birefringence>none</Birefringence>

    <Optical2v>none</Optical2v>

    <RefractionIndices>none</RefractionIndices>

    <OpticalProperties>reflectivity: R = 48% to 60%</OpticalProperties>

    <InterferenceFigure>opaque</InterferenceFigure>

    <Occurrence>low-temperature hydrothermal veins (occasionally found in medium to high-temperature deposits) associated with sulfides, gold, and other tellurides</Occurrence>

    <Location>Transylvania; Western Australia; California; Cripple Creek, Colorado</Location>

    <Properties>often forms skeletal crystal groups that resemble ancient cuneiform writing</Properties>

    <Abundance>very rare</Abundance>

    <Miscellaneous>a.k.a. graphic tellurium</Miscellaneous>

    <ChemicalClass>

      <Dana>

        <Class>Sulfides</Class>

        <Member>2.12.13.3</Member>

      </Dana>

      <Strunz>

        <Class>Sulfides and sulphosalts</Class>

        <Member>II/D.16-20</Member>

      </Strunz>

    </ChemicalClass>

  </Mineral>



  <Mineral>

    <Name>CALAVERITE</Name>

    <DiscreditedNames/>

    <Formula>AuTe2</Formula>

    <CrystalSystem>monoclinic</CrystalSystem>

    <Hardness>2½ - 3</Hardness>

    <SpecificGravity>9.0 - 9.3</SpecificGravity>

    <Luster>bright metallic</Luster>

    <Cleavage>none, conchoidal fracture</Cleavage>

    <Color>silvery-white to pale bronze to brassy yellow</Color>

    <Habit>small bladed crystals that are frequently twinned; often massive or granular</Habit>

    <Twinning>twinning common on {101}, {310}, and {111}</Twinning>

    <Tenacity>very brittle</Tenacity>

    <Streak>yellowish to greenish-gray</Streak>

    <Pyrognostics>soluble in HNO3, leaving behind a rusty yellow residue (Au); dissolves in hot, concentrated H2SO4, producing a dark reddish-violet solution (Te); fuses extremely easily at 1; fusion of a mixture of powdered mineral and sodium carbonate flux on a charcoal plate yields a small globule of gold (or electrum if the silver content is high enough) and gives a bluish-green flame (Te)</Pyrognostics>

    <Birefringence>none</Birefringence>

    <Optical2v>none</Optical2v>

    <RefractionIndices>none</RefractionIndices>

    <OpticalProperties>weakly anisotropic</OpticalProperties>

    <InterferenceFigure>opaque</InterferenceFigure>

    <Occurrence>low-temperature hydrothermal veins (occasionally found in medium to high-temperature deposits) associated with sulfides, native gold, and other tellurides</Occurrence>

    <Location>Transylvania; Western Australia; California; Ontario; Cripple Creek, Colorado</Location>

    <Properties>crystals are striated parallel to their length</Properties>

    <Abundance>very rare</Abundance>

    <Miscellaneous>twinned crystals frequently form interlocking patterns that resemble writing; always contains a small amount of silver</Miscellaneous>

    <ChemicalClass>

      <Dana>

        <Class>Sulfides</Class>

        <Member>2.12.13.2</Member>

      </Dana>

      <Strunz>

        <Class>Sulfides and sulphosalts</Class>

        <Member>II/D.16-40</Member>

      </Strunz>

    </ChemicalClass>

  </Mineral>



  <Mineral>

    <Name>SILVER</Name>

    <DiscreditedNames/>

    <Formula>Ag</Formula>

    <CrystalSystem>isometric</CrystalSystem>

    <Hardness>2½ - 3</Hardness>

    <SpecificGravity>10.5</SpecificGravity>

    <Luster>metallic when fresh, dull and submetallic otherwise</Luster>

    <Cleavage>none, hackly fracture</Cleavage>

    <Color>silver-white, often tarnishes black</Color>

    <Habit>arborescent, branching, massive, dendritic, wire-like</Habit>

    <Twinning>penetration twinning on {111}; also twinning on {100} and {111} as arborescent growths</Twinning>

    <Tenacity>ductile, sectile, malleable, flexible, inelastic</Tenacity>

    <Streak>silver-white</Streak>

    <Pyrognostics>fuses easily at 2 to a bright silvery-white globule which takes on a faint, dark red coating of silver oxide when exposed to the oxidizing portion of the flame while on a charcoal plate; quickly tarnishes when exposed to H2S fumes; soluble in HNO3 (can be brought back out of solution by dropping a piece of copper metal into the nitric acid); adding HCl (or common table salt) to the nitric acid solution yields a white, curdled precipitate of AgCl</Pyrognostics>

    <Birefringence>none</Birefringence>

    <Optical2v>none</Optical2v>

    <RefractionIndices>none</RefractionIndices>

    <OpticalProperties>reflectivity: R = 95%</OpticalProperties>

    <InterferenceFigure>opaque</InterferenceFigure>

    <Occurrence>oxidized zone of hydrothermal ore bodies; primary mineral associated with sulfides and copper/nickel ores</Occurrence>

    <Location>Norway; Saxony; Ontario; Northwest Territories; Bohemia; Mexico; Michigan</Location>

    <Properties>the best known conductor of heat and electricity</Properties>

    <Abundance>very rare</Abundance>

    <Miscellaneous>shows incomplete extinction in polished sections</Miscellaneous>

    <ChemicalClass>

      <Dana>

        <Class>Native Elements</Class>

        <Member>1.1.1.2</Member>

      </Dana>

      <Strunz>

        <Class>Elements</Class>

        <Member>I/A.01-20</Member>

      </Strunz>

    </ChemicalClass>

  </Mineral>



</MineralDatabase>