Crystals
Beryl
Cyclosilicate mineral Be3Al2Si6O18 Hexagonal crystal system Mohs 7.5–8 Uniaxial negative Channel water and alkalis Emerald, aquamarine, morganite, heliodor Goshenite and red beryl Beryl: One Hexagonal Framework, an Entire Family of...
Beryl
Cyclosilicate mineral Be3Al2Si6O18 Hexagonal crystal system Mohs 7.5–8 Uniaxial negative Channel water and alkalis Emerald, aquamarine, morganite, heliodor Goshenite and red beryl Beryl: One Hexagonal Framework, an Entire Family of...
Alum
Hydrated double-sulfate family Potassium alum: KAl(SO4)2·12H2O Isometric symmetry and octahedral habit Mohs approximately 2–2.5 Colorless potassium alum; violet chrome alum Water-soluble and humidity-sensitive Alum: Hydrated Double Sulfates, Octahedral Growth, and...
Alum
Hydrated double-sulfate family Potassium alum: KAl(SO4)2·12H2O Isometric symmetry and octahedral habit Mohs approximately 2–2.5 Colorless potassium alum; violet chrome alum Water-soluble and humidity-sensitive Alum: Hydrated Double Sulfates, Octahedral Growth, and...
Agate
Patterned microcrystalline silica Quartz and chalcedony family Wall-lining, waterline, eye, lace, and tube structures Translucent to opaque Mohs approximately 6.5–7 Natural, dyed, heated, filled, and assembled material occur Agate: Layered...
Agate
Patterned microcrystalline silica Quartz and chalcedony family Wall-lining, waterline, eye, lace, and tube structures Translucent to opaque Mohs approximately 6.5–7 Natural, dyed, heated, filled, and assembled material occur Agate: Layered...
Amazonite
Blue-green variety of microcline feldspar KAlSi3O8 Triclinic symmetry and tartan twinning Mohs approximately 6–6.5 Two cleavages meeting near 90° Commonly perthitic, with pale albite lamellae Amazonite: Blue-Green Microcline, Perthitic Pattern,...
Amazonite
Blue-green variety of microcline feldspar KAlSi3O8 Triclinic symmetry and tartan twinning Mohs approximately 6–6.5 Two cleavages meeting near 90° Commonly perthitic, with pale albite lamellae Amazonite: Blue-Green Microcline, Perthitic Pattern,...
Bismuth
Chemical element 83 Symbol Bi Trigonal-rhombohedral structure Strong diamagnetism Melting point approximately 271.4 °C Thin-film interference color Mohs approximately 2–2.5 Density approximately 9.78 g/cm³ Bismuth: Elemental Metal, Hopper Geometry, and...
Bismuth
Chemical element 83 Symbol Bi Trigonal-rhombohedral structure Strong diamagnetism Melting point approximately 271.4 °C Thin-film interference color Mohs approximately 2–2.5 Density approximately 9.78 g/cm³ Bismuth: Elemental Metal, Hopper Geometry, and...
Bornite
Copper–iron sulfide Cu5FeS4 Orthorhombic at room temperature Mohs approximately 3 Approximately 63.3% copper by mass Iridescent tarnish Porphyry, vein, skarn, and supergene settings Bornite: Copper-Rich Sulfide, Peacock Tarnish, and the...
Bornite
Copper–iron sulfide Cu5FeS4 Orthorhombic at room temperature Mohs approximately 3 Approximately 63.3% copper by mass Iridescent tarnish Porphyry, vein, skarn, and supergene settings Bornite: Copper-Rich Sulfide, Peacock Tarnish, and the...