Topaz is a highly prized silicate mineral often found in well-formed, prismatic crystals within granitic pegmatites. Collectors look for its characteristic high hardness and perfect basal cleavage, which distinguishes it from common quartz. While often blue, it naturally occurs in a wide spectrum of colors ranging from colorless to vibrant sherry, pink, and yellow hues.
Spotting topaz in the field
Field marks- 1
Prismatic crystals with lengthwise striations and a distinctly wedge-shaped termination
- 2
Perfect basal cleavage, so it can split flat straight across the crystal
- 3
Hardness 8 and unusually heavy for a pale, glassy mineral
Weight is the surprise with topaz: it is noticeably denser than quartz and picking one out of a handful of pale crystals is often done by heft. The perfect basal cleavage is both the diagnostic and the hazard, because a knock in the field can split a good crystal cleanly in half. Topaz Mountain in Utah's Thomas Range is the accessible American locality, where sherry-colored crystals sit in cavities in rhyolite and weather out into the talus below.
Before you collect
Topaz Mountain's sherry-colored crystals fade to colorless with prolonged exposure to sunlight, sometimes within weeks. Store and display them out of direct sun if you want the color to last, and be aware that colorless crystals in the same talus may once have been sherry.
Straight answers
- Is it worth cutting?
- The basal cleavage dominates everything. Orient the table of a faceted stone at an angle to the cleavage plane, never parallel to it, or the stone can part on the wheel or later in wear.
- What is it really worth?
- Inexpensive for common material, and most blue topaz in jewelry is irradiated colorless topaz. Natural imperial and sherry topaz carry real premiums.
- Can you legally keep it?
- Topaz Mountain is BLM land open to personal-use collecting without a permit, which makes it one of the best free gem-collecting destinations in the country. Texas topaz occurs on private ranches that charge for access.
Where it is worth going
- Topaz MountainThomas Range, Juab County, Utah
Free collecting on BLM land. Sherry topaz in rhyolite cavities and weathered out into the talus.
- Mason CountyCentral Texas
Blue topaz, the Texas state gem, on private ranches that offer paid access.
Often confused with
Topaz vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Topaz is heavier, harder at 8, and has a perfect basal cleavage that quartz completely lacks.
How to tell apart: Beryl is hexagonal in cross-section. Topaz is orthorhombic, giving a more diamond-shaped section, and topaz cleaves.
Often found alongside topaz
Minerals reported to co-occur with topaz. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂SiO₄(F,OH)₂
- Mohs hardness
- 8
- Density
- 3.49-3.57 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals with Multi-faceted Terminations
- Cleavage
- Perfect Basal
- Fluorescence
- Weak to Moderate; Varies By Locality
- Rarity
- Common
- Uses
- Gemstone, Collector
- Host rock
- Granite Pegmatites, Rhyolite Cavities, And High-temperature Hydrothermal Veins
- Typical price
- $10-100 per gram for rough; significantly higher for rare collector colors like imperial or sherry
Where rockhounds find topaz
42 mapped spotsClassic worldwide localities
- Brazil
- Pakistan
- Sri Lanka
- Russia
- USA
- Mexico
U.S. states with topaz
Each link opens a state-specific list of mapped rockhounding spots that produce topaz.
Field-hunting tip
Look in granite pegmatites, rhyolite cavities, and high-temperature hydrothermal veins country, the host setting where topaz typically forms. If you start seeing quartz, microcline, fluorite in float, you are in the right ground. Field specimens usually show a prismatic crystals with multi-faceted terminations habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Colorado, Utah, New Hampshire. Start trip planning there.
Common questions
How do you identify topaz?+
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Find topaz on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
