mineral

Tumbled howlite

Howlite, Ca₂B₅SiO₉(OH)₅

AI-generated identification · may be incorrect

White to gray, opaque, porcelain-like stone with dark gray veining; Mohs hardness 3–3.5, vitreous to dull luster, triclinic crystal structure, and poor cleavage. The rounded shape indicates tumbling or polishing.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is a hydrated calcium borosilicate that forms as nodules in evaporite-associated borate deposits, commonly in sedimentary environments. It is geologically young relative to many crystalline rocks, with major deposits known from the Cenozoic western United States.

Uses & applications

Used mainly for carvings, beads, cabochons, and ornamental specimens; it is sometimes dyed to imitate turquoise. Its softness makes it unsuitable for heavy-wear jewelry or construction.

Geological facts

Natural howlite is typically white with thin, irregular gray or black veining; turquoise-blue material sold as “turquenite” is often dyed howlite.

Field identification & locations

Common sources include California and Nova Scotia, Canada. Identify it by its low hardness, chalky white color, irregular web-like veins, and ability to scratch with a steel knife; a photo alone cannot exclude magnesite, marble, or dyed material.