Crystals
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...
Muscovite
Dioctahedral mica KAl2(AlSi3O10)(OH,F)2 Monoclinic, commonly 2M1 Perfect basal cleavage Mohs about 2–2.5 along the sheets Elastic transparent leaves Pearly to vitreous luster Fuchsite and fine white-mica forms Muscovite: The Shimmering...
Muscovite
Dioctahedral mica KAl2(AlSi3O10)(OH,F)2 Monoclinic, commonly 2M1 Perfect basal cleavage Mohs about 2–2.5 along the sheets Elastic transparent leaves Pearly to vitreous luster Fuchsite and fine white-mica forms Muscovite: The Shimmering...
Vesuvianite
Vesuvianite • traditional synonym: idocrase Representative formula: Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4 Complex calcium–aluminum sorosilicate Tetragonal • square-section prisms and stepped pyramids Mohs about 6–7 • specific gravity about 3.32–3.45 Vitreous to resinous •...
Vesuvianite
Vesuvianite • traditional synonym: idocrase Representative formula: Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4 Complex calcium–aluminum sorosilicate Tetragonal • square-section prisms and stepped pyramids Mohs about 6–7 • specific gravity about 3.32–3.45 Vitreous to resinous •...
Vanadinite
Vanadinite • lead chlorovanadate Pb5(VO4)3Cl Apatite supergroup • vanadate member Hexagonal • short prisms and barrel-shaped crystals Red, orange, yellow, and reddish brown Mohs about 2.5–3 • specific gravity about...
Vanadinite
Vanadinite • lead chlorovanadate Pb5(VO4)3Cl Apatite supergroup • vanadate member Hexagonal • short prisms and barrel-shaped crystals Red, orange, yellow, and reddish brown Mohs about 2.5–3 • specific gravity about...
Rhyolite
Felsic volcanic rock Commonly 69–80 wt% SiO2 Fine-grained or glassy equivalent of granitic composition Quartz, alkali feldspar, and plagioclase are characteristic Aphanitic, porphyritic, flow-banded, or brecciated Obsidian, perlite, pumice, and...
Rhyolite
Felsic volcanic rock Commonly 69–80 wt% SiO2 Fine-grained or glassy equivalent of granitic composition Quartz, alkali feldspar, and plagioclase are characteristic Aphanitic, porphyritic, flow-banded, or brecciated Obsidian, perlite, pumice, and...