mineral
Howlite
Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)
Hardness: 3.5 on Mohs scale; Color: White to milky grey with black or dark brown veining; Luster: Sub-vitreous to earthy; Crystal Structure: Monoclinic; Cleavage: None (conchoidal fracture)
- Hardness
- 3
- Color
- White to milky grey with black or dark brown veining
- Luster
- Sub-vitreous to earthy
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Physical properties
Hardness: 3.5 on Mohs scale; Color: White to milky grey with black or dark brown veining; Luster: Sub-vitreous to earthy; Crystal Structure: Monoclinic; Cleavage: None (conchoidal fracture)
Formation & geological history
Formed in evaporite deposits in arid environments through the precipitation of boron-rich waters into sedimentary beds. Often found in nodules or cauliflower-like masses.
Uses & applications
Commonly used as a gemstone for jewelry, beads, and carvings. It is also a significant industrial source of boron. Due to its porous nature, it is frequently dyed blue to imitate turquoise.
Geological facts
Named after Henry How, a 19th-century Canadian mineralogist who first described it in Nova Scotia. It is often referred to as 'White Turquoise' or 'Buffalo Turquoise' in the jewelry market, although it is unrelated to actual turquoise.
Field identification & locations
Identified by its white porcelain-like appearance and distinctive erratic grey veining. It is relatively soft and can be scratched by a copper coin. Commonly found in California, USA, and Nova Scotia, Canada.
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Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
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Mineral
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Mineral/Rock