{ "mineral_database": { "acknowledgement": "mineral data Copyright and courtesy of Geology Park LLC and theGeoZone.com", "mineral": [ { "name": "AUGITE", "discredited_names": "", "formula": "(Ca,Na)(Mg,Fe,Al)(Si,Al)2O6", "crystal_system": "monoclinic", "hardness": "5 - 6", "specific_gravity": "3.2 - 3.4", "luster": "vitreous", "cleavage": "imperfect 90º; prismatic {110}", "color": "black", "habit": "stubby prismatic crystals", "twinning": "twinning on {100} and {001}", "tenacity": "brittle", "streak": "greenish-gray", "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)", "birefringence": "0.026", "optical2v": "25º; - 83º;", "refraction_indices": "a = 1.662-1.735 ß = 1.670-1.741 y = 1.688-1.761", "optical_properties": "inclined extinction", "interference_figure": "biaxial (+)", "occurrence": "found in intermediate, basic, and ultrabasic igneous rocks", "location": "fine crystals found in Greenland; Italy; Bushveld Complex, South Africa; Stillwater Complex, Montana", "properties": "shows high relief and green to olive-green color in thin section", "abundance": "very common", "miscellaneous": "titanium-rich varieties show strong pleochroism, beautiful violet color, and zoned \"hourglass\" structure", "chemical_class": { "dana": { "class": "", "member": "" }, "strunz": { "class": "", "member": "" } } }, { "name": "GOLD", "discredited_names": "", "formula": "Au", "crystal_system": "isometric", "hardness": "2½ - 3", "specific_gravity": "15.0 - 19.3", "luster": "metallic", "cleavage": "hackly fracture", "color": "various shades of yellow", "habit": "rare octahedral crystals, arborescent, filiform, dendritic, reticulated", "twinning": "twinning on {111}", "tenacity": "sectile, ductile, malleable, flexible, inelastic", "streak": "yellow", "pyrognostics": "soluble only in aqua regia; fuses easily at 3; impervious to any flux", "birefringence": "none", "optical2v": "none", "refraction_indices": "none", "optical_properties": "very high reflectivity: R = 74%", "interference_figure": "opaque", "occurrence": "hydrothermal veins associated with silicic igneous rocks; also found in alluvial deposits", "location": "South Africa; Russia; Canada; Australia; Ghana; California; South Dakota; Nevada; Arizona; Alaska; Utah; Colorado", "properties": "very thin sheets transmit a feeble greenish light", "abundance": "very rare", "miscellaneous": "excellent conductor of heat and electricity", "chemical_class": { "dana": { "class": "Native Elements", "member": "1.1.1.1" }, "strunz": { "class": "Elements", "member": "I\/A.01-40" } } }, { "name": "SYLVANITE", "discredited_names": "", "formula": "(Au,Ag)Te2", "crystal_system": "monoclinic", "hardness": "1½ - 2", "specific_gravity": "8.0 - 8.2", "luster": "brilliant metallic", "cleavage": "perfect {010}", "color": "silvery-white", "habit": "bladed crystals, also granular masses, forms skeletal or cuneiform-like intergrowths", "twinning": "twinning on {110} which produces distinctive skeletal crystal groups", "tenacity": "brittle, but thin shavings are sectile", "streak": "gray", "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)", "birefringence": "none", "optical2v": "none", "refraction_indices": "none", "optical_properties": "reflectivity: R = 48% to 60%", "interference_figure": "opaque", "occurrence": "low-temperature hydrothermal veins (occasionally found in medium to high-temperature deposits) associated with sulfides, gold, and other tellurides", "location": "Transylvania; Western Australia; California; Cripple Creek, Colorado", "properties": "often forms skeletal crystal groups that resemble ancient cuneiform writing", "abundance": "very rare", "miscellaneous": "a.k.a. graphic tellurium", "chemical_class": { "dana": { "class": "Sulfides", "member": "2.12.13.3" }, "strunz": { "class": "Sulfides and sulphosalts", "member": "II\/D.16-20" } } }, { "name": "CALAVERITE", "discredited_names": "", "formula": "AuTe2", "crystal_system": "monoclinic", "hardness": "2½ - 3", "specific_gravity": "9.0 - 9.3", "luster": "bright metallic", "cleavage": "none, conchoidal fracture", "color": "silvery-white to pale bronze to brassy yellow", "habit": "small bladed crystals that are frequently twinned; often massive or granular", "twinning": "twinning common on {101}, {310}, and {111}", "tenacity": "very brittle", "streak": "yellowish to greenish-gray", "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)", "birefringence": "none", "optical2v": "none", "refraction_indices": "none", "optical_properties": "weakly anisotropic", "interference_figure": "opaque", "occurrence": "low-temperature hydrothermal veins (occasionally found in medium to high-temperature deposits) associated with sulfides, native gold, and other tellurides", "location": "Transylvania; Western Australia; California; Ontario; Cripple Creek, Colorado", "properties": "crystals are striated parallel to their length", "abundance": "very rare", "miscellaneous": "twinned crystals frequently form interlocking patterns that resemble writing; always contains a small amount of silver", "chemical_class": { "dana": { "class": "Sulfides", "member": "2.12.13.2" }, "strunz": { "class": "Sulfides and sulphosalts", "member": "II\/D.16-40" } } }, { "name": "SILVER", "discredited_names": "", "formula": "Ag", "crystal_system": "isometric", "hardness": "2½ - 3", "specific_gravity": "10.5", "luster": "metallic when fresh, dull and submetallic otherwise", "cleavage": "none, hackly fracture", "color": "silver-white, often tarnishes black", "habit": "arborescent, branching, massive, dendritic, wire-like", "twinning": "penetration twinning on {111}; also twinning on {100} and {111} as arborescent growths", "tenacity": "ductile, sectile, malleable, flexible, inelastic", "streak": "silver-white", "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", "birefringence": "none", "optical2v": "none", "refraction_indices": "none", "optical_properties": "reflectivity: R = 95%", "interference_figure": "opaque", "occurrence": "oxidized zone of hydrothermal ore bodies; primary mineral associated with sulfides and copper\/nickel ores", "location": "Norway; Saxony; Ontario; Northwest Territories; Bohemia; Mexico; Michigan", "properties": "the best known conductor of heat and electricity", "abundance": "very rare", "miscellaneous": "shows incomplete extinction in polished sections", "chemical_class": { "dana": { "class": "Native Elements", "member": "1.1.1.2" }, "strunz": { "class": "Elements", "member": "I\/A.01-20" } } } ] } }