Crystals
Dumortierite
Aluminum borosilicate Al7BO3(SiO4)3O3 Orthorhombic crystal system Mohs approximately 7–8.5 Fibrous blue to violet aggregates Dumortierite: Blue Fibers Shaped by Boron, Pressure, and Metamorphic Heat Dumortierite is a complex aluminum borosilicate...
Dumortierite
Aluminum borosilicate Al7BO3(SiO4)3O3 Orthorhombic crystal system Mohs approximately 7–8.5 Fibrous blue to violet aggregates Dumortierite: Blue Fibers Shaped by Boron, Pressure, and Metamorphic Heat Dumortierite is a complex aluminum borosilicate...
Heliotrope
Chalcedony variety Silicon dioxide, SiO2 Mohs 6.5–7 Deep green with red iron-oxide spots Traditional March birthstone Heliotrope Bloodstone: Deep Green Chalcedony Marked by Red Iron Heliotrope, widely known as bloodstone,...
Heliotrope
Chalcedony variety Silicon dioxide, SiO2 Mohs 6.5–7 Deep green with red iron-oxide spots Traditional March birthstone Heliotrope Bloodstone: Deep Green Chalcedony Marked by Red Iron Heliotrope, widely known as bloodstone,...
Diamond
Carbon mineral Chemical symbol C Isometric crystal system Mohs 10 Refractive index 2.417 Diamond: Carbon Lattice, Spectral Fire, and the Engineering of Light Diamond is carbon arranged in an exceptionally...
Diamond
Carbon mineral Chemical symbol C Isometric crystal system Mohs 10 Refractive index 2.417 Diamond: Carbon Lattice, Spectral Fire, and the Engineering of Light Diamond is carbon arranged in an exceptionally...
Granite
Felsic intrusive igneous rock Quartz + alkali feldspar + plagioclase Coarse interlocking crystals Commonly about 65–77% SiO2 Typical density about 2.6–2.75 g/cm³ Granite: The Crystalline Framework of Continents Granite is...
Granite
Felsic intrusive igneous rock Quartz + alkali feldspar + plagioclase Coarse interlocking crystals Commonly about 65–77% SiO2 Typical density about 2.6–2.75 g/cm³ Granite: The Crystalline Framework of Continents Granite is...
Girasol
Optical description, not one mineral species Common opal: SiO2·nH2O Quartz: SiO2 Diffuse blue-white internal glow Cabochons, spheres, beads, and freeforms Girasol: Two Silica Materials, One Floating Internal Light Girasol is...
Girasol
Optical description, not one mineral species Common opal: SiO2·nH2O Quartz: SiO2 Diffuse blue-white internal glow Cabochons, spheres, beads, and freeforms Girasol: Two Silica Materials, One Floating Internal Light Girasol is...
Fluorite
Calcium fluoride Chemical formula CaF2 Isometric crystal system Perfect octahedral cleavage Mohs hardness 4 Fluorite: Cubic Color, Octahedral Cleavage, and the Mineral Behind Fluorescence Fluorite is calcium fluoride arranged in...
Fluorite
Calcium fluoride Chemical formula CaF2 Isometric crystal system Perfect octahedral cleavage Mohs hardness 4 Fluorite: Cubic Color, Octahedral Cleavage, and the Mineral Behind Fluorescence Fluorite is calcium fluoride arranged in...