mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

AI-generated identification · may be incorrect

Hardness: 3.5 on Mohs scale; Color: Chalky white with web-like black, grey, or brown veins; Luster: Sub-vitreous to earthy; Crystal Structure: Monoclinic; Cleavage: None; Specific Gravity: 2.53–2.59

Hardness: 3
Color: Chalky white with web-like black, grey, or brown veins
Luster: Sub-vitreous to earthy

Identified March 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits, usually found as nodules, masses, or sometimes as tabular crystals in continental or saline lake environments. Primarily found in deposits from the Neogene period (2.5 million to 23 million years ago).

Uses & applications

Commonly used for decorative carvings, jewelry (tumbled stones or beads), and as a base for imitation turquoise because its porous nature allows it to take blue or green dye well.

Geological facts

Howlite was first discovered by Henry How in 1868 near Windsor, Nova Scotia. It is often colloquially known as 'white turquoise' or 'cabbie stone' in the trade, though those names are geologically inaccurate.

Field identification & locations

Identify in the field by its distinct white color with web-like veining and its low hardness (it can be scratched by a copper coin). Major deposits are located in Canada (Nova Scotia), the USA (California and Nevada), and parts of Turkey.