mineral

Howlite

Howlite (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Chalky white to milky grey with dark grey, black, or brown spider-web veining; Luster: Sub-vitreous, silky, or earthy (dull); Crystal Structure: Monoclinic (forms in nodules rather than crystals); Cleavage: Indistinct; Specific Gravity: 2.53–2.59.

Hardness: 3
Luster: Sub-vitreous, silky, or earthy (dull)

Identified March 16, 2026More mineral →

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Physical properties

Formation & geological history

Howlite is an evaporite mineral, typically formed in continental saline basins as a result of the boron-rich waters reacting with silicate and calcium sources. It is often found in nodules that look like cauliflower heads.

Uses & applications

Commonly used for decorative carvings, beads, and jewelry. Due to its porous nature, it is frequently dyed blue to imitate turquoise (known as 'Turquenite') or red to imitate coral. It also serves as a source of borax for industrial use.

Geological facts

It was first discovered in 1868 near Windsor, Nova Scotia, by Canadian mineralogist Henry How, after whom it is named. Because it is so soft, it is very easy to carve but must be handled carefully to avoid scratches.

Field identification & locations

Identify in the field by its distinct white cauliflower-like appearance and webbed grey veining. Major deposits are found in Tick Canyon, California, USA, and New Brunswick, Canada. It is often misidentified as turquoise or magnesite when dyed.