Tourmaline
Image: “Jon Zander (Digon3)" (CC BY-SA 3.0)
Mineral NameTourmaline
Chemical Formula(Na,Ca)(Mg,Fe,Mn,Li,Al)3Al6(Si6O18)(BO3)3(OH,F)4
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavageindistinct to poor
Fractureconchoidal
Specific Gravity3.06
Colorspink, tan, light brown
Transparencytranslucent
Type LocalityBrazil, Afghanistan, Pakistan, USA (Maine, California)
Mineral GroupSilicates
Usesjewelry, industrial, collector
Associated Mineralsquartz, feldspar, lepidolite, beryl
Raritycommon
Description
This specimen features a dense cluster of elongated, prismatic tourmaline crystals, predominantly pinkish-tan to light brown, exhibiting prominent vertical striations on their faces. The crystals form a rough, columnar aggregate, with some areas showing a slightly darker, more opaque appearance.
Geological Context
Tourmaline typically forms in igneous and metamorphic rocks, particularly in granitic pegmatites and hydrothermal veins, where it crystallizes from boron-rich fluids. It is also found in detrital sediments due to its durability.
