mineral
Tumbled howlite (probable)
Howlite, Ca₂B₅SiO₉(OH)₅
AI-generated identification · may be incorrectWhite to chalky gray with irregular dark gray veining; dull to waxy luster and typically massive rather than visibly crystalline. Mohs hardness 3–3.5, brittle, opaque, and relatively light (specific gravity about 2.5–2.6).
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Physical properties
White to chalky gray with irregular dark gray veining; dull to waxy luster and typically massive rather than visibly crystalline. Mohs hardness 3–3.5, brittle, opaque, and relatively light (specific gravity about 2.5–2.6).
Formation & geological history
Howlite forms as a borate mineral in evaporite-associated clay deposits, commonly in arid sedimentary basins; its exact age depends on the deposit, often Cenozoic. The rounded surface indicates tumbling and polishing.
Uses & applications
Commonly sold as inexpensive cabochons, beads, carvings, and meditation stones; it is also frequently dyed turquoise-blue and marketed as “turquenite.” It has little industrial use.
Geological facts
The specimen resembles howlite, though white magnesite or veined marble can look similar. Howlite is too soft for durable high-wear jewelry and may scratch readily.
Field identification & locations
Identify by its chalky white body, distinctive thin gray-black spiderweb veining, low hardness, and light weight; vinegar will not strongly fizz. Major sources include California and Nova Scotia, Canada.
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