mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

AI-generated identification · may be incorrect

Hardness: 3.5 on Mohs scale; Color: Chalky white with fine grey, black, or dark brown veins; Luster: Sub-vitreous to earthy; Crystal structure: Monoclinic (usually found as nodules); Specific Gravity: 2.53–2.59

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

Identified March 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits within sedimentary basins, typically associated with borate minerals in arid environments. Often found in continental lake beds.

Uses & applications

Used primarily in lapidary work for beads, carvings, and jewelry. Due to its porous nature, it is frequently dyed blue to imitate Turquoise or red to imitate Coral.

Geological facts

Howlite was first discovered near Windsor, Nova Scotia in 1868 by Henry How, a Canadian chemist and geologist. In its natural white state, it is sometimes marketed as 'White Turquoise' or 'White Buffalo Stone.'

Field identification & locations

Identify by its characteristic 'spider web' veining and chalky texture. It is much softer than true turquoise (which is 5-6 on Mohs scale). Common locations include California and Nevada, USA, and Nova Scotia, Canada.