Howlite
Howlite (IMA-approved silicoborate mineral) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Monoclinic; typically found in massive, nodular, or cauliflower-like habits. Rare prismatic crystals.
Mineral Group
Borates (Silicoborate subgroup)
Chemical Formula
Ca2B5SiO9(OH)5
Formation Process
Sedimentary/Evaporite; forms in continental evaporite basins where boron-rich waters concentrate, often as a replacement mineral in nodules.
About This Crystal
An opaque, porcelain-white to milky-white mineral featuring a sub-vitreous to earthy luster. This specimen is polished into a heart shape and exhibits a characteristic web-like matrix of brown-to-grey veins (host rock inclusions).
Physical Characteristics
Color: White with brown/grey veins; Streak: White; Cleavage: None (massive habit); Fracture: Conchoidal to even; Specific Gravity: 2.45–2.58; Tenacity: Brittle; Fluorescence: Occasionally weak orange under LWUV.
Optical Properties
Refractive Index: 1.583–1.605; Birefringence: 0.022; Optically Biaxial (-); Opaque, so limited optical phenomena other than surface luster.
Hardness & Durability
Origin Region
Notably Nova Scotia (Canada), California (USA), and Turkey. Found in evaporite deposits related to boron-rich volcanic activity.
Hardness & Durability
Mohs Hardness: 3.5; relatively soft and susceptible to scratching from minerals like quartz or steel. Poor toughness due to porosity.
Care & Maintenance
Avoid ultrasonic/steam cleaners. Clean with warm soapy water and a soft cloth. Highly porous; avoid dyes, perfumes, and oils as they will stain the stone. Store separately from harder gemstones.
Rarity & Value
Abundant and inexpensive. Primarily valued for its ability to mimic Turquoise or Lapis Lazuli when dyed. Natural 'White Buffalo' style specimens are popular in Southwestern jewelry.
Special Characteristics
Highly porous nature makes it the primary candidate for dyeing (sold as 'Turquenite' or dyed red as 'Coral' imitations). Naturally occurring spider-web matrix pattern.
Lore & History
Named after Henry How, who first described it in 1868. Traditionally associated with calming the mind and reducing insomnia. In crystal healing, it is used for the Crown Chakra and believed to promote patience and emotional balance.