mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Chalky white with fine grey or black veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic (usually found in nodules); Cleavage: Indistinct; Specific Gravity: 2.53–2.59

Hardness: 3
Color: Chalky white with fine grey or black veining
Luster: Sub-vitreous to pearly

Identified March 9, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is an evaporite mineral, typically forming in continental salt lakes and arid environments from alkaline solutions enriched with boron. It is commonly found in nodules that look like cauliflower heads.

Uses & applications

Predominantly used for ornamental purposes, such as jewelry, beads, and figurines. Because of its porous nature, it is frequently dyed blue to imitate Turquoise or red to imitate Coral.

Geological facts

It was first discovered near Windsor, Nova Scotia, in 1868 by Henry How, a Canadian mineralogist, for whom it is named. Natural howlite is often called 'White Turquoise' by vendors, though it is chemically unrelated.

Field identification & locations

Identify in the field by its distinctive 'spider-web' or 'matrix' veining and chalky texture. It is softer than quartz and will not scratch glass. Common locations include Nova Scotia, Canada, and various sites in California and Nevada, USA.

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