Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
trigonalcommonSilicates
Tourmaline
(Na,Ca)(Li,Mg,Fe,Mn,Al)3Al6(BO3)3Si6O18(OH)4
The image shows a dark, likely black or very dark green, prismatic tourmaline crystal with characteristic vertical striations along its length. The crystal appears opaque to translucent and has a natural, somewhat rough termination.
Tourmaline Physical Properties
Mohs Hardness
7Crystal System
trigonalLuster
vitreousStreak Color
whiteCleavage
indistinct/poor basalFracture
uneven to conchoidalSpecific Gravity
3.06Colors
black, dark green, dark blueTransparency
translucentType Locality
Momeik, Mogok, Sagaing District, Mandalay Division, Burma (Myanmar)Mineral Group
SilicatesUses
jewelry, collector specimens, industrial (minor)Associated Minerals
quartz, feldspar, mica, beryl, spodumeneRarity
commonGeological Context
Tourmaline is commonly found in granite pegmatites, metamorphic rocks like schists and gneisses, and hydrothermal veins. It forms from boron-rich fluids during the late stages of igneous crystallization or during regional metamorphism.
