Tunellite Locality: Boron , Kramer District, Kern County , California , USA ( Locality at mindat.org ) Size: miniature, 5 x 4.3 x 2.5 cm Tunellite A very nice cluster of well-formed crystals to 3 cm from this classic locality. Few were saved as they came out, and specimens of this quality are hard to obtain today. Note that this rare borate is stable. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Tunellite
Tunellite is an IMA-recognized mineral species in the borate class, with the chemical formula SrB₆O₉(OH)₂·3H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/a).
Key properties: Mohs hardness 2.5; specific gravity 2.4; Subvitreous, pearly on {100} faces and cleavages luster; optically biaxial.
IMA symbol Tnl, IMA status: approved, named in 1961.
A rare secondary mineral formed in borate deposits.
It is found associated with Inderite, kurnakovite, ulexite, hydroboracite, colemanite, realgar, stibnite, celestine, analcime.
The mineral was named to honor Dr. George Gerard Tunell, Jr. (1900–1996), Professor of Geology, University of California, Los Angeles, California, USA.