Crystals
Aventurine
Quartz with reflective mineral inclusions SiO2 Trigonal quartz structure Mohs approximately 6.5–7 Optical effect: aventurescence Fuchsite, hematite, goethite, ilmenite, and mica inclusions Aventurine: Quartz, Reflective Inclusions, and the Moving Light...
Aventurine
Quartz with reflective mineral inclusions SiO2 Trigonal quartz structure Mohs approximately 6.5–7 Optical effect: aventurescence Fuchsite, hematite, goethite, ilmenite, and mica inclusions Aventurine: Quartz, Reflective Inclusions, and the Moving Light...
Azurite
Copper carbonate hydroxide Cu3(CO3)2(OH)2 Monoclinic crystal system Mohs 3.5–4 Specific gravity approximately 3.7–3.9 Commonly associated with malachite Secondary copper mineral Azurite: Copper Blue, Oxidation-Zone Crystals, and the Slow Green Turn...
Azurite
Copper carbonate hydroxide Cu3(CO3)2(OH)2 Monoclinic crystal system Mohs 3.5–4 Specific gravity approximately 3.7–3.9 Commonly associated with malachite Secondary copper mineral Azurite: Copper Blue, Oxidation-Zone Crystals, and the Slow Green Turn...
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,...