Crystals
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,...
Sardonyx
Parallel-banded chalcedony SiO2 Sard red-brown layers with white, gray, or black onyx bands Polycrystalline quartz aggregate with variable moganite Mohs hardness about 6.5–7 Specific gravity commonly about 2.58–2.64 Waxy to...
Sardonyx
Parallel-banded chalcedony SiO2 Sard red-brown layers with white, gray, or black onyx bands Polycrystalline quartz aggregate with variable moganite Mohs hardness about 6.5–7 Specific gravity commonly about 2.58–2.64 Waxy to...
Sapphire
Gem variety of corundum Al2O3 All gem corundum outside the red ruby range Trigonal crystal system Mohs hardness 9 Specific gravity about 3.98–4.10 Uniaxial negative with directional color Metamorphic and...
Sapphire
Gem variety of corundum Al2O3 All gem corundum outside the red ruby range Trigonal crystal system Mohs hardness 9 Specific gravity about 3.98–4.10 Uniaxial negative with directional color Metamorphic and...