The most important mineral component of lapis lazuli is lazurite(25% to 40%), a tectosilicate mineral with the formula (Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)]. Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Some samples of lapis lazuli contain augite; diopside; enstatite; mica; hauynite; hornblende, nosean, and sulfur-rich löllingite geyerite. Lapis lazuli was discovered around 6,000 years ago in the Hindu-Kush Mountains of present-day Afghanistan. Today, Afghanistan continues to be the leading producer of the lapis lazuli.
Anyolite is a metamorphic rock composed of intergrown green zoisite (Ca2Al3(SiO4)(Si2O7)O(OH) ), black/dark green pargasite (NaCa2(Mg4Al)(Si6Al2)O22(OH)2 ) and ruby (Al2O3:Cr).
A pure crystal of corundum (Al2O3 ) is colorless. However, if just 1% of the Al3+ ions are replaced with Cr3+ ions, the mineral becomes deep red in color and is known as ruby.
Bauxite is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium. Bauxite consists mostly of the aluminium minerals gibbsite (Al(OH)3), boehmite (Y-AlO(OH)) and diaspore (α-AlO(OH)), mixed with the two iron oxides goethite (FeO(OH)) and haematite (Fe2O3), the aluminium clay mineral kaolinite (Al2Si2O5(OH)4) and small amounts of anatase (TiO2) and ilmenite (FeTiO3 or FeO.TiO2).
This piece is from Yatağan / Turkey
Azurite (Cu3(CO3)2(OH)2) mineral in granite.
Silver ore from Uşak / Turkey
Brown, Black Obsidian
Obsidian is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly.