mineral
Tumbled howlite (likely)
Howlite, Ca₂B₅SiO₉(OH)₅
AI-generated identification · may be incorrectWhite to pale gray, opaque, with distinctive dark gray veining; typically vitreous to dull luster and massive rather than visibly crystalline. Mohs hardness 3.5, uneven fracture, and relatively low specific gravity (~2.5); the rounded shape indicates tumbling and polishing.
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Physical properties
White to pale gray, opaque, with distinctive dark gray veining; typically vitreous to dull luster and massive rather than visibly crystalline. Mohs hardness 3.5, uneven fracture, and relatively low specific gravity (~2.5); the rounded shape indicates tumbling and polishing.
Formation & geological history
Howlite is a borate mineral formed in evaporite-related boron-rich clay deposits, commonly as nodules or irregular masses. It is geologically young compared with many crystalline rocks, often associated with Cenozoic continental basin deposits.
Uses & applications
Used mainly for carvings, beads, cabochons, and inexpensive decorative objects; it is also commonly dyed to imitate turquoise. Not generally used as a construction stone.
Geological facts
The specimen’s appearance is consistent with howlite, though magnesite and dyed or veined marble can look similar. Howlite’s porous surface accepts dyes readily, making blue “turquenite” a common trade product.
Field identification & locations
Common localities include California and Nevada, USA, and parts of Canada and Turkey. Confirm with hardness and acid testing: it should scratch easily with a steel blade, while dilute acid may weakly react if magnesite is present.
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Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous