Crystals
Unakite
Unakite • metasomatically altered granitic rock Pink potassium feldspar • commonly orthoclase or microcline Green epidote • commonly replacing plagioclase Colorless to smoky-gray quartz Coarse-grained, mottled, massive, or weakly foliated...
Unakite
Unakite • metasomatically altered granitic rock Pink potassium feldspar • commonly orthoclase or microcline Green epidote • commonly replacing plagioclase Colorless to smoky-gray quartz Coarse-grained, mottled, massive, or weakly foliated...
Topaz
Topaz • orthorhombic nesosilicate Al2SiO4(F,OH)2 Mohs 8 • specific gravity about 3.49–3.57 Perfect basal cleavage on {001} Vitreous luster • biaxial positive Commonly prismatic with vertical striations Imperial colors range...
Topaz
Topaz • orthorhombic nesosilicate Al2SiO4(F,OH)2 Mohs 8 • specific gravity about 3.49–3.57 Perfect basal cleavage on {001} Vitreous luster • biaxial positive Commonly prismatic with vertical striations Imperial colors range...
Sodalite
Sodalite group feldspathoid Na8(Al6Si6O24)Cl2 Isometric crystal system Rare dodecahedra; commonly massive or granular Mohs 5.5–6 Specific gravity about 2.27–2.33 White material is commonly calcite or feldspathic matrix Fluorescence may be...
Sodalite
Sodalite group feldspathoid Na8(Al6Si6O24)Cl2 Isometric crystal system Rare dodecahedra; commonly massive or granular Mohs 5.5–6 Specific gravity about 2.27–2.33 White material is commonly calcite or feldspathic matrix Fluorescence may be...
Silicon
Silicon, element symbol Si Atomic number 14 Group 14 metalloid Standard atomic weight 28.085 Diamond-cubic crystal structure Density about 2.33 g/cm³ Melting point about 1414 °C Indirect band gap about...
Silicon
Silicon, element symbol Si Atomic number 14 Group 14 metalloid Standard atomic weight 28.085 Diamond-cubic crystal structure Density about 2.33 g/cm³ Melting point about 1414 °C Indirect band gap about...
Serpentine
Serpentine subgroup of hydrated sheet silicates Ideal Mg3Si2O5(OH)4 Principal Mg-rich species: antigorite, lizardite, and chrysotile Serpentinite is a rock dominated by serpentine minerals Typical species hardness about 2.5–3.5 Dense lapidary...
Serpentine
Serpentine subgroup of hydrated sheet silicates Ideal Mg3Si2O5(OH)4 Principal Mg-rich species: antigorite, lizardite, and chrysotile Serpentinite is a rock dominated by serpentine minerals Typical species hardness about 2.5–3.5 Dense lapidary...
Selenite
Transparent crystalline variety of gypsum CaSO4·2H2O Monoclinic crystal system Mohs hardness 2 Specific gravity about 2.30–2.33 Perfect sheet-forming cleavage Flexible but inelastic in thin flakes Biaxial positive optical character Evaporites,...
Selenite
Transparent crystalline variety of gypsum CaSO4·2H2O Monoclinic crystal system Mohs hardness 2 Specific gravity about 2.30–2.33 Perfect sheet-forming cleavage Flexible but inelastic in thin flakes Biaxial positive optical character Evaporites,...