Minerals with Metallic Luster

Minerals with Metallic Luster Hardness Harder than glass Softer than glass but harder than fingernail Softer than fingernail Cleavage Cleavage absent, poor or not visible Cleavage good to excellent Cleavage absent, poor, or not visible Cleavage absent, poor, or not visible Mineral Name Streak Other diagnostic properties Dark grey to black Greenish black Silvery, dark grey to black; h: 6-6.5; s.g.: 5.2; octahedron crystals or may occur massive to granular; strongly attracted to a magnet Redbrown Dark grey to black Yellowbrown Greenish black Copper Grey Brass yellow; h: 6-6.5; s.g.: 5.2; conchoidal fracture; cube or pyritohedron crystals Steel grey, reddish-silver, bright silver; h: 5-6; s.g.: 5; may appear platy; may weakly attract a magnet; can also occur as nonmetallic, dull to earthy, red-brown masses Silver-gray, tarnishes dull; h: 2.5; s.g.: 7.6 (feels heavy); good cubic cleavage (3 @ 90); cube or octahedron crystals Metallic to submetallic to silky, dark brown or black; h: 5-5.5; s.g.: 4.3; conchoidal fracture; Golden to brassy yellow; h: 3.5-4; s.g.: 4.2; irregular fracture; typically massive, tetrahedron crystals Copper color, tarnishes to brown or green; h: 2.5-3; s.g.: 8.9 (feels heavy); hackly fracture, typically nuggets or dendritic masses Silvery gray; h: 1-2; s.g.: 2.2; commonly massive, occasionally platy; slippery feel; easily rubs off on fingers, clothes or paper Minerals with Non-metallic Luster Hardness Cleavage light colored minerals Softer than glass but harder than fingernail Cleavage good to excellent Cleavage absent, poor, or not visible Cleavage good to excellent Softer than fingernail Translucent, white to pale grey; h: 6; s.g.: 2.7; two cleavages at nearly 90 ; striations visible on cleavage surface Translucent, pink to red, grey or white; h: 6; s.g.: 2.6; two cleavages at nearly 90o; may show exsolution lamellae Gray, brown, red or blue; h: 9; s.g.: 4; hexagonal (six sided) crystals common Cleavage absent, poor, or not visible Cleavage absent, poor, or not visible Fe3O4 Pyrite FeS2 Hematite Fe2O3 Galena PbS Goethite FeO(OH) Chalcopyrite CuFeS2 Copper Cu Graphite C (chemical composition) Pale blue, green, white or grey; h; 5.5-7; s.g.; 3.5-3.7; two cleavages not at 90o; long bladed crystals Harder than glass Magnetite Mineral Name Other diagnostic properties o Cleavage good to excellent (chemical composition) Transparent, colorless, white, grey or other colors; vitreous (glassy); h: 7; s.g.: 2.65; conchoidal fracture; massive or hexagonal (6 sided) crystals Transparent, pale green, vitreous (glassy); h: 6.5-7; s.g.: 3.2; commonly found as masses of small grains Translucent to transparent, colorless, purple, yellow, green, blue; h: 4; s.g.: 3.1-3.5; excellent octahedral cleavage (4 directions); cube or octahedron crystals; white streak White, grey, yellowish to colorless; h: 3; s.g.: 2.7; three cleavages not at 90o (rhombohedral); effervesces in HCl; often transparent White, grey pink, colorless; h: 3.5-4; s.g.: 2.8-2.9; three cleavages not at 90o (rhombohedral); effervesces in dilute HCl when powdered White to colorless, yellow, pink; h: 2.5; s.g.: 2.2; three cleavages at 90o (cubic); salty taste Transparent, pale green, white, red, blue, vitreous (glassy); h: 5; s.g.: 3.2; conchoidal fracture; hexagonal (6 sided) crystals Opaque, yellow brown, earthy masses; h: 4-5.5; s.g.: 3.5; yellow-brown streak Pale to dark reddish brown, earthy to dull luster; h: 1-3; s.g: 2-2.5; often contains spheroidal-shaped particles; not a true mineral Colorless to brown; h: 2-2.5; s.g.: 2.8-2.9; one excellent cleavage; transparent, flexible and elastic in thin sheets; Transparent, colorless to white; h: 2 (very soft); s.g.: 2.3-2.4; one excellent cleavage, two good cleavages (total= three cleavages not at 90o); may also occur as massive aggregates or with a fibrous habit and silky luster; white streak Pale to dark reddish brown, earthy to dull luster; h: 1-3; s.g: 2-2.5; often contains spheroidal-shaped particles; not a true mineral Yellow, resinous luster; h: 1.5-2.5; s.g.: 2.1; conchoidal fracture; massive or crystals; white to pale yellow streak smells like sulfur or rotten eggs White, cream, grey brown, dull to earthy luster; h: 2-2.5; s.g.: 2.6; powdery to greasy feel; earthy odor when moistened White, grey, green, brown; pearly luster; h: 1 (very soft); s.g.: 2.5-2.8; may form in thin plates; greasy to soapy feel; Sodium plagioclase feldspar (Albite) NaAlSi3O8 Potassium feldspar (Orthoclase) KAlSi3O8 Kyanite Al2SiO5 Corundum Al2O3 Quartz SiO2 varieties: milky (white), rose (pink), smoky (gray), amethyst (violet) Olivine (Mg,Fe)2SiO4 Fluorite CaF2 Calcite CaCO3 Dolomite CaMg(CO3)2 Halite NaCl Apatite Ca5(PO4)3(Cl,F,OH) Limonite Fe2O3H2O Bauxite Hydrous Al oxide Muscovite KAl2(Si3Al)O10(OH,F)2 Gypsum CaSO42H2O Bauxite Hydrous Al oxide Sulfur S Kaolinite Al2Si2O5(OH)4 Talc Mg3Si4O10(OH)2 Minerals with Non-metallic Luster Hardness Cleavage Cleavage good to excellent Other diagnostic properties Calcium plagioclase feldspar (Anorthite) Translucent, pink to red, grey or white; h: 6; s.g.: 2.6; two cleavages at nearly 90o; may show exsolution lamellae Potassium feldspar Dark green to black; dull to vitreous (glassy); h: 5-6; s.g.: 3.2-3.6; two good cleavages at nearly 90o ; breaks into blocks; forms short, stubby crystals Pyroxene Dark green to black to greenish black; vitreous (glassy); h: 5-6; s.g.: 3-3.4; two excellent cleavages at nearly 60o and 120o ; forms long, thin crystals Blue, green, white or grey; h; 5.5-7; s.g.; 3.5-3.7; two cleavages not at 90o; long bladed crystals Harder than glass Gray, brown, red or blue; h: 9; s.g.: 4; hexagonal (six sided) crystals common dark colored minerals Cleavage absent, poor, or not visible Cleavage good to excellent Softer than glass but harder than fingernail Cleavage absent, poor, or not visible Red-brown to brown; h: 7-7.5; s.g.: 3.7; one cleavage present but difficult to see; intergrown (twinned), X shaped crystals common Transparent, dark brown to black; vitreous (glassy); h: 7; s.g.: 2.65; conchoidal fracture; massive or hexagonal (6 sided) crystals Transparent, vitreous (glassy), red to reddish brown (other colors possible); h: 6.5-7.5; s.g: 4.3; conchoidal fracture; equant crystals typically dodecahedrons (12 sided) Transparent, olive green, vitreous (glassy); h: 6.5-7; s.g.: 3.2; commonly found as masses of small grains Silvery, dark grey to black; h: 6-6.5; s.g.: 5.2; octahedron crystals or may occur massive to granular; strongly attracted to a magnet; dark grey to black streak Brown to red-brown, dull to earthy or submetallic luster (may also be grey, reddishsilver, bright silver); h: 5-6; s.g.: 5; may weakly attract a magnet; red-brown streak; may show rounded ooids Submetallic to resinous, brown, yellow-brown to red-brown; h: 3.5-4; s.g: 3.9-4.2; good cleavage in 6 directions; pale yellow streak smells like sulfur or rotten eggs Translucent to transparent, purple, green, blue yellow, colorless; h: 4; s.g.: 3.1-3.5; excellent octahedral cleavage (4 directions); cube or octahedron crystals; white streak Black to dark brown; h: 2.5-3; s.g.: 3.3; one excellent cleavage; flexible and elastic in thin sheets Silky to submetallic to metallic, dark brown or black; h: 5-5.5; s.g.: 4.3; conchoidal fracture; yellow-brown streak Transparent, green, brown, red, vitreous (glassy); h: 5; s.g.: 3.2; conchoidal fracture; hexagonal (6 sided) crystals Copper color, tarnishes to brown or green; h: 2.5-3; s.g.: 8.9 (feels heavy); hackly fracture, typically nuggets or dendritic masses, copper streak Dark to pale reddish brown, earthy to dull luster; h: 1-3; s.g: 2-2.5; often contains spheroidal-shaped particles; not a true mineral Opaque, yellow brown, earthy masses; h: 4-5.5; s.g.: 3.5; yellow-brown streak Softer than fingernail Cleavage good to excellent Cleavage absent, poor, or not visible Mineral Name (chemical composition) Translucent, dark grey to blue-grey to black, may be iridescent; h: 6; s.g.: 2.7; two cleavages at nearly 90o; striations visible on cleavage surface Green to blackish green; h: 2-2.5; s.g.: 2.6-3.3; one excellent cleavage; thin sheets are flexible but not elastic Dark to pale reddish brown, earthy to dull luster; h: 1-3; s.g: 2-2.5; often contains spheroidal-shaped particles; not a true mineral CaAl2Si2O8 (Orthoclase) KAlSi3O8 (Augite) (Ca,Mg,Fe)2Si2O6 Amphibole (Hornblende) Ca2(Fe,Mg)4Al(Si7Al)O22(OH)2) Kyanite Al2SiO5 Corundum Al2O3 Staurolite Fe2Al9Si4O23(OH) Smoky quartz SiO2 Garnet (Ca,Fe,Mg,Mn)3(Fe,Al)2(SiO4)3 Olivine (Mg,Fe)2SiO4 Magnetite Fe3O4 Hematite Fe2O3 Sphalerite ZnS Fluorite CaF2 Biotite K(Fe,Mg)3AlSi3O10(OH)2 Goethite FeO(OH) Apatite Ca5(PO4)3(Cl,F,OH) Copper Cu Bauxite Hydrous Al oxide Limonite Fe2O3H2O Chlorite (Fe,Mg,Al,Fe)6(Si,Al)4O10(OH,O)8 Bauxite Hydrous Al oxide