Crystal guide
How to Identify Topaz
Al₂SiO₄(F,OH)₂
Topaz is an aluminum silicate fluoride (Al₂SiO₄(F,OH)₂) at Mohs 8 with perfect basal cleavage. Identify it by orthorhombic prisms, glassy luster, notable heft (SG ~3.5), sherry-to-blue-to-pink colors, and a cleavage plane quartz never shows.
About Topaz
Topaz is an aluminum silicate fluoride (Al₂SiO₄(F,OH)₂) at Mohs 8 with perfect basal cleavage. Identify it by orthorhombic prisms, glassy luster, notable heft (SG ~3.5), sherry-to-blue-to-pink colors, and a cleavage plane quartz never shows.
Topaz is filed under crystals in the RockScan directory. Composition: Aluminum silicate fluoride hydroxide. It forms via pegmatites and rhyolite cavities. Typical occurrence: Brazil, Pakistan, Russia, USA (Utah). For the broader method, see how to identify rock types.
Topaz properties
| Mohs hardness | 8 |
|---|---|
| Class | crystal |
| Scientific name | Al₂SiO₄(F,OH)₂ |
| Color | Sherry, blue (often treated), pink, imperial |
| Luster | Vitreous |
| Crystal system / texture | Orthorhombic |
| Composition | Aluminum silicate fluoride hydroxide |
| Formation | Pegmatites and rhyolite cavities |
| Occurrence | Brazil, Pakistan, Russia, USA (Utah) |
How to identify Topaz
- Mohs 8 — scratches quartz; only corundum-family stones scratch it.
- Perfect basal cleavage plane plus striated orthorhombic prisms.
- Sherry, pink, imperial orange, or treated blue; dense feel (SG ~3.5).
Lookalikes to rule out
- Citrine: Citrine is quartz (Mohs 7) with no cleavage; topaz reaches Mohs 8 with a perfect basal cleavage plane.
- Aquamarine: Aquamarine is hexagonal beryl with subtle cleavage; topaz shows orthorhombic prisms and one perfect cleavage.
- Glass: Glass is soft (~5.5) with bubbles; topaz is hard (8) with crisp crystal faces and cleavage flats.
Photo tips for Topaz ID
- Shoot the basal cleavage plane and prism striations; cleavage is topaz's signature.
- Document sherry, pink, and blue color variants accurately — most blues are treated.
- Photograph heft and size; dense topaz feels weightier than quartz of equal size.
Snap one specimen in natural light, then open the result in the online studio or the rock identifier app.
Topaz FAQ
How do you identify topaz?
Check Mohs 8 hardness plus a perfect basal cleavage plane. Citrine and quartz lack cleavage and scratch easier.
Topaz vs citrine?
Citrine is quartz (7) with no cleavage; topaz is harder (8) with one perfect cleavage and greater density.
Is blue topaz natural?
Most commercial blue topaz is irradiated and heated colorless topaz — same mineral, treated color. Swiss and London blues dominate treated stock.
How to identify topaz
Topaz and citrine get swapped in shops because both run golden — hardness plus cleavage ends the debate:
- Hardness 8: scratches quartz and glass effortlessly; citrine (7) cannot scratch topaz back.
- Basal cleavage: one perfect flat plane across the crystal — quartz-family stones never show it.
- Prism habit: orthorhombic prisms with vertical striations and rich terminations.
- Heft: SG ~3.5 feels dense next to quartz (~2.65) of the same size.
- Photo confirm: cleavage-plane and striation macros with a hardness note, then RockScan against citrine and aquamarine.
Topaz vs citrine vs aquamarine vs glass
- Citrine: softer quartz with hexagonal habit and zero cleavage.
- Aquamarine: hexagonal beryl with watery zoning; topaz cleavage and density differ.
- Glass: soft with bubbles and mold marks; no cleavage or crystal striations.
Photo tips for topaz cleavage
Angle light to catch the mirror-flat cleavage plane beside striated prism faces. Compare citrine, aquamarine, and quartz guides, then confirm in the online studio or rock identifier app.
Related crystals to compare
Browse all: rocks · minerals · crystals · directory · what rock is this · rock vs mineral vs crystal. Confirm with the online studio or rock identifier app.