Pinnoite Locality: Inder B deposit and salt dome, Atyrau (Gur'yev) , Atyrau Oblysy (Atyrau Oblast') , Kazakhstan ( Locality at mindat.org ) Size: 8 x 6 x 4 cm. A very rich and beautiful specimen of this rare species from the famous borate deposits at Lake Inder. Glistening, translucent aggregates to just under 1 cm abound on this 3-dimensional matrix. Ex. Martin Zinn Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Pinnoite
A colorless-to-yellowish magnesium borate forming radial fibrous clusters.
Intro adapted from Wikipedia (CC BY-SA).
Pinnoite is an IMA-recognized mineral species in the borate class, with the chemical formula MgB₂O(OH)₆.
It crystallizes in the tetragonal crystal system (space group P4_2).
Key properties: Mohs hardness 3.5; specific gravity 2.27; Vitreous luster; refractive index 1.57; optically uniaxial.
IMA symbol Pno, grandfathered status — known before the IMA’s founding, named in 1884.
is typically found in bedded marine salt deposits; an efflorescence around salt springs and lakes.
It is found associated with Boracite, kaliborite.
The mineral was named to honor Oberbergrat Pinno, Chief Councillor of Mines, Halle, Germany.