Crystals
Moonstone
Feldspar with adularescence Classic orthoclase–albite intergrowth Mohs approximately 6–6.5 Specific gravity approximately 2.56–2.60 Blue, white, or silver floating sheen Peach, cream, gray, and colorless bodies Two cleavage directions near 90...
Moonstone
Feldspar with adularescence Classic orthoclase–albite intergrowth Mohs approximately 6–6.5 Specific gravity approximately 2.56–2.60 Blue, white, or silver floating sheen Peach, cream, gray, and colorless bodies Two cleavage directions near 90...
Obsidian
Natural volcanic glass Typically 70–78% SiO2 Amorphous mineraloid Mohs approximately 5–5.5 Conchoidal fracture Gold and silver sheen Rainbow and fire varieties Snowflake spherulites Hydration, perlite, and archaeology Obsidian: Volcanic Glass...
Obsidian
Natural volcanic glass Typically 70–78% SiO2 Amorphous mineraloid Mohs approximately 5–5.5 Conchoidal fracture Gold and silver sheen Rainbow and fire varieties Snowflake spherulites Hydration, perlite, and archaeology Obsidian: Volcanic Glass...
Lepidolite
Lithium-rich mica series K(Li,Al)3(Si,Al)4O10(F,OH)2 Trioctahedral sheet silicate Typically monoclinic polytypes Perfect basal cleavage Mohs approximately 2.5–4 Lilac, lavender, rose, violet-gray, and silver Late-stage LCT pegmatites Historic source material in rubidium...
Lepidolite
Lithium-rich mica series K(Li,Al)3(Si,Al)4O10(F,OH)2 Trioctahedral sheet silicate Typically monoclinic polytypes Perfect basal cleavage Mohs approximately 2.5–4 Lilac, lavender, rose, violet-gray, and silver Late-stage LCT pegmatites Historic source material in rubidium...
Magnesite
Magnesium carbonate MgCO3 Calcite-group mineral Trigonal crystal system Mohs approximately 3.5–4.5 Perfect rhombohedral cleavage Carbonation of magnesium-rich rock Naturally pale, often dyed Magnesite: The White Carbonate Behind Many Colors Magnesite...
Magnesite
Magnesium carbonate MgCO3 Calcite-group mineral Trigonal crystal system Mohs approximately 3.5–4.5 Perfect rhombohedral cleavage Carbonation of magnesium-rich rock Naturally pale, often dyed Magnesite: The White Carbonate Behind Many Colors Magnesite...
Lizardite
Serpentine-group phyllosilicate Mg3Si2O5(OH)4 Platy layered structure Mohs approximately 2.5–3.5 Waxy to greasy luster Forms through serpentinization Commonly associated with magnetite Named for the Lizard Peninsula Lizardite: The Platy Serpentine Mineral...
Lizardite
Serpentine-group phyllosilicate Mg3Si2O5(OH)4 Platy layered structure Mohs approximately 2.5–3.5 Waxy to greasy luster Forms through serpentinization Commonly associated with magnetite Named for the Lizard Peninsula Lizardite: The Platy Serpentine Mineral...
Magnetite
Iron oxide mineral Fe3O4 Inverse spinel structure Isometric crystal system Mohs approximately 5.5–6.5 Black streak and metallic luster Strong ferrimagnetism Curie temperature near 580°C Major iron ore and geological recorder...
Magnetite
Iron oxide mineral Fe3O4 Inverse spinel structure Isometric crystal system Mohs approximately 5.5–6.5 Black streak and metallic luster Strong ferrimagnetism Curie temperature near 580°C Major iron ore and geological recorder...