Studenitsite

Studenitsite is a rare borate mineral with chemical formula of NaCa2[B9O14(OH)4]·2H2O.

Studenitsite
General
CategoryPhylloborates
Formula
(repeating unit)		NaCa2[B9O14(OH4)]·2H2O
Strunz classification6.GB.05
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/c
Unit cella = 11.4994 Å, b = 12.5878 Å
c = 10.5297 Å; β = 99.416°; Z = 4
Identification
Formula mass528 g/mol
ColorColorless to light dirty-yellow and light grey
Crystal habitClusters of flattened wedge-shaped crystals
TenacityFragile
Mohs scale hardness5.5–6
LusterVitreous
StreakWhite
DiaphaneityTransparent
Specific gravity2.29
Optical propertiesBiaxial (+)
Refractive indexnα = 1.532 nβ = 1.538 nγ = 1.564
Birefringenceδ = 0.032
2V angleMeasured: 54°
Other characteristicsNamed after Studenica, a cloister near the discovery locality.
References[1][2][3]

Studenitsite has a vitreous luster, a Mohs hardness of 6 and color of light-dirty yellow.[1] It is a monoclinic mineral and belongs to the space group P2/c.[4] The basic unit of the crystal structure[B9O14(OH)4]5-layers has a Miller Index of (001).[4] Studenitsite has a low surface relief, which means the measure of the relative difference between the index of refraction of the mineral and surrounding medium is small. Birefringence is the difference between two principal indices of refraction of a uniaxial crystal. Studenitsite has a maximum birefringent value of δ = 0.032. Studenitsite has three indices of refraction. Their values are nα = 1.532, nβ = 1.538, nγ = 1.564. Indices of refraction are the ratio of the light's speed in the mineral and the medium.[1]

Studenitsite is an extremely rare mineral that has only been found in the Piskaya deposit, Yarondolskii Basin, on the Ibar River, 280 km south of Belgrade, Serbia. The deposit is classified as a volcanogenic-sedimentary borate deposit with clay and carbonate minerals.[2][3] It occurs associated with colemanite, howlite, ulexite and pentahydroborite.[3] It is a rare but important mineral for understanding the volcanic settings in Western Serbia.[5] It was named after the Studenica cloister near the discovery location.[3]

See also

References
  1. Mindat.org
  2. Webmineral data
  3. Handbook of Mineralogy
  4. Jambor, L.John.(1996) New Mineral Names.American Mineralogist, 81, 1284.
  5. http://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Studenitsite
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