Ulexite (TV Rock)
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)
Mineral NameUlexite (TV Rock)
Chemical FormulaNaCa[B5O6(OH)6]·5H2O
Mohs Hardness2.5
Crystal Systemtriclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {010}, good on {110}
Fractureuneven
Specific Gravity1.96
Colorswhite, colorless, gray
Transparencytransparent
Type LocalityBoron, Kramer District, Kern County, California, USA
Mineral GroupBorates
Usesoptical demonstrations, source of boron, collector
Associated Mineralsgypsum, borax, colemanite, kernite, halite
Raritycommon
Description
This specimen is a translucent, off-white to colorless block of ulexite, displaying its characteristic fibrous structure. It clearly demonstrates its 'TV rock' property by transmitting the red color of an object placed behind it, appearing as a distinct red band within the mineral.
Geological Context
Ulexite is a hydrous sodium calcium borate that forms as an evaporite mineral in arid regions, typically in playa lake deposits or saline lake environments. It is commonly found in borate deposits.
