mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Milky white to grey with black or dark brown veining; Luster: Sub-vitreous to dull; Crystal structure: Monoclinic; Specific Gravity: 2.53-2.59.

Hardness: 3
Color: Milky white to grey with black or dark brown veining
Luster: Sub-vitreous to dull

Identified May 19, 2026More mineral →

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Physical properties

Hardness: 3.5 on Mohs scale; Color: Milky white to grey with black or dark brown veining; Luster: Sub-vitreous to dull; Crystal structure: Monoclinic; Specific Gravity: 2.53-2.59.

Formation & geological history

Formed in evaporite deposits in arid environments through the interaction of borates and silicate-rich fluids. Often found in nodules that look like cauliflower heads.

Uses & applications

Commonly used as a decorative stone, in jewelry (often dyed to resemble turquoise or lapis lazuli due to its porous nature), and as a minor source of boron.

Geological facts

Howlite is often called 'White Turquoise' or 'White Buffalo Stone' in the jewelry trade. It was first discovered in Nova Scotia by Henry How in 1868.

Field identification & locations

Identify in the field by its characteristic spider-web veining and relatively low hardness (can be scratched by a copper coin). Found primarily in Tick Canyon, California, and Nova Scotia, Canada.

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