mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: White to milky gray with dark gray or black veins; Luster: Sub-vitreous to dull/earthy; Crystal Structure: Monoclinic (usually found in massive/nodular form); Cleavage: Indistinct; Specific Gravity: 2.53-2.59

Hardness: 3
Color: White to milky gray with dark gray or black veins
Luster: Sub-vitreous to dull/earthy

Identified June 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits in arid environments. It is often found in borax-rich sedimentary basins. Most deposits date from the Cenozoic era.

Uses & applications

Primarily used as an ornamental stone and for jewelry. Because of its porous nature and white color, it is frequently dyed to imitate turquoise or lapis lazuli. Also used as a minor source of borax.

Geological facts

Howlite was first discovered by Henry How in 1868 near Windsor, Nova Scotia. In its natural white state, it is sometimes called 'white turquoise' or 'white buffalo stone', though these trade names are geologically inaccurate.

Field identification & locations

Identify by its opaque white massive appearance and distinct spider-web like gray veining. It can be scratched by a copper penny or steel knife. Found commonly in Canada (Nova Scotia) and the USA (California).

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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Metamorphic Rock

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mineral