tuzlaite

{{Infobox mineral | name = Tuzlaite | category = Borates | image = | caption = | formula = NaCaB5O8(OH)2 · 3H2O | IMAsymbol =Tuz | molweight = | strunz =6.EC.25 | system = Monoclinic | class =2/m - Prismatic | symmetry = P21/c | unit cell = a = 6.506(1) b = 13.280(3) c = 11.462(3) β = 92.97(2)◦ Z=4 | color = Colorless to White | habit = Prismatic crystals, elongated along [001] | twinning = | cleavage = On {001}, perfect | fracture = | tenacity = | mohs = 2 - 3 | luster = Silky to pearly | polish = | refractive = | opticalprop = Biaxial Positive | birefringence = | dispersion = | pleochroism = | fluorescence=None | absorption = | streak =White | gravity = | density =2.23 g/cm | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = | other = | references = }} Tuzlaite is a borate mineral, associated with halides, named after the Tuzla salt mines in Bosnia and Hercegovina. A multitude of rare evaporate minerals have been discovered there, it being the only major evaporate deposit in the Balkans. This mineral has been approved as tuzlaite by the International Commission on New Minerals and Mineral Names.

== Occurrence == Tuzlaite is found alongside several rare evaporates such as northupite, searlesite, and bradleyite. Between the layers of salt, there are approximately 50m thick layers of grey to black dolomitic marls that occasionally get cut by white veinlets composed of the mineral tuzlaite. These veinlets can be surrounded by a coronitic halite phase that can be dissolved off with H2O, leaving us with colorless to white crystals of tuzlaite up to 0.5mm in length. Most of these crystals can be intergrown, but some are suitable for X-ray single-crystal structure analysis.