Crystals
Tree agate
Inclusion-bearing chalcedony Silicon dioxide, SiO2 Milky white to semi-translucent host Mohs approximately 6.5–7 Green dendritic and branch-like inclusions Tree Agate: Milky Chalcedony, Green Dendrites, and the Geometry of Mineral Forests...
Tree agate
Inclusion-bearing chalcedony Silicon dioxide, SiO2 Milky white to semi-translucent host Mohs approximately 6.5–7 Green dendritic and branch-like inclusions Tree Agate: Milky Chalcedony, Green Dendrites, and the Geometry of Mineral Forests...
Dalmatian jasper
Trade name: Dalmatian Jasper Feldspar-rich igneous rock Dark amphibole spots Mohs approximately 6–6.5 Classic source: Chihuahua, Mexico Dalmatian Stone: Feldspar, Dark Amphibole, and a Naturally Speckled Igneous Pattern Dalmatian stone,...
Dalmatian jasper
Trade name: Dalmatian Jasper Feldspar-rich igneous rock Dark amphibole spots Mohs approximately 6–6.5 Classic source: Chihuahua, Mexico Dalmatian Stone: Feldspar, Dark Amphibole, and a Naturally Speckled Igneous Pattern Dalmatian stone,...
Brecciated jasper
Jasper and chalcedony Angular breccia texture Silica-rich, commonly SiO2 Mohs approximately 6.5–7 Iron-oxide reds Brecciated Jasper: Fracture, Silica Cement, and a Stone Reassembled Brecciated jasper is a naturally fragmented and...
Brecciated jasper
Jasper and chalcedony Angular breccia texture Silica-rich, commonly SiO2 Mohs approximately 6.5–7 Iron-oxide reds Brecciated Jasper: Fracture, Silica Cement, and a Stone Reassembled Brecciated jasper is a naturally fragmented and...
Coral
Biogenic and organic gem materials CaCO3 skeletons in many groups Protein-rich axis in black coral Recent coral: Mohs approximately 3–4 Aragonitic blue coral Colonial skeletal architecture Dye and resin treatment...
Coral
Biogenic and organic gem materials CaCO3 skeletons in many groups Protein-rich axis in black coral Recent coral: Mohs approximately 3–4 Aragonitic blue coral Colonial skeletal architecture Dye and resin treatment...
Desert rose
Sulfate mineral rosette Gypsum or barite CaSO4·2H2O BaSO4 Sand-rich bladed crystals Desert Rose: Gypsum and Barite Rosettes Formed by Evaporation, Sand, and Time Desert rose is a descriptive name for...
Desert rose
Sulfate mineral rosette Gypsum or barite CaSO4·2H2O BaSO4 Sand-rich bladed crystals Desert Rose: Gypsum and Barite Rosettes Formed by Evaporation, Sand, and Time Desert rose is a descriptive name for...
Iceland spar
Transparent optical calcite Calcium carbonate, CaCO3 Trigonal crystal system Mohs hardness 3 Exceptionally strong birefringence Perfect rhombohedral cleavage Iceland Spar: Clear Calcite, Double Refraction, and the Geometry of Polarized Light...
Iceland spar
Transparent optical calcite Calcium carbonate, CaCO3 Trigonal crystal system Mohs hardness 3 Exceptionally strong birefringence Perfect rhombohedral cleavage Iceland Spar: Clear Calcite, Double Refraction, and the Geometry of Polarized Light...