Howlite
White to gray calcium borosilicate hydroxide with gray-black veining. Widely dyed blue or turquoise-blue and sold as a turquoise imitation — dyed howlite is the most common turquoise simulant in the commercial market. Strong blue LW UV fluorescence is a key natural identification feature.
Physical & Optical Properties
Key Differentiators
- Natural white/gray color with distinctive gray-black veining resembling spider-web turquoise matrix
- Very low hardness 3.5 — easily scratched by a fingernail or copper coin
- Strong blue LW UV fluorescence (natural undyed material) — diagnostic
- Dyed blue = widely sold as turquoise simulant; acetone definitively removes blue dye
- SG 2.53 lighter than turquoise (2.60–2.85)
Common Simulants
- Turquoise (target of imitation): Dyed howlite is the simulant; turquoise is the target. Turquoise: H 5–6, SG 2.60–2.85, RI 1.610–1.650, no dye on acetone test, no strong blue LW fluorescence.
- Magnesite (also dyed as turquoise): Magnesite (H 3.5–4.5, SG ~3.0) is also dyed blue to imitate turquoise. Higher SG than howlite distinguishes them.
Commonly Confused With
Commonly confused with: Turquoise.
Treatments
- Dyed Blue or Turquoise-Blue (primary treatment)
- Dyed Other Colors (red, green, purple, etc.)
- Wax or Resin Impregnation
Price Context
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
About Howlite
White to gray calcium borosilicate hydroxide with gray-black veining. Widely dyed blue or turquoise-blue and sold as a turquoise imitation — dyed howlite is the most common turquoise simulant in the commercial market. Strong blue LW UV fluorescence is a key natural identification feature.
Identifying a howlite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
Try GemID Free →