mineral

Dyed Howlite (Dyed Red)

Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Naturally white with grey/black veins, dyed red here; Luster: Sub-vitreous to earthy; Crystal structure: Monoclinic; Cleavage: None visible in nodules; Specific Gravity: 2.53–2.59.

Hardness: 3
Color: Naturally white with grey/black veins, dyed red here
Luster: Sub-vitreous to earthy

Identified April 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits, usually as nodules in sedimentary environments. Most commercial specimens are mined in California, USA, or Nova Scotia, Canada.

Uses & applications

Used primarily in lapidary work, jewelry (beads, cabochons), and as a decorative stone. Because of its porous nature, it is frequently dyed to imitate turquoise (blue) or red coral.

Geological facts

Howlite is named after Henry How, the chemist who first described it in 1868. It is naturally very porous, which makes it one of the most common stones used for artificial dyeing in the gem industry.

Field identification & locations

Identify by its low hardness (it can be scratched with a penny or knife) and the distinctive 'spider-web' dark veining. In the field, look for cauliflower-like nodules; the red color is a sure sign it has been treated.

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