Austinite is an attractive secondary arsenic mineral often found as radiating, acicular sprays or botryoidal crusts. It is most easily identified by its vibrant yellow-green fluorescence under short-wave ultraviolet light, which makes it a favorite among collectors of fluorescent minerals.
Is this austinite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch austinite with a known reference. Austinite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Austinite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Austinite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellow, green, brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, radiating clusters, botryoidal, crusts.
Often confused with
Austinite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Austinite leaves white, Conichalcite leaves light green.
How to tell apart: Adelite is the harder of the two (Mohs 5 vs. 4).
How to tell apart: Streak differs — Austinite leaves white, Descloizite leaves orange to brownish-red; luster reads vitreous on Austinite and greasy to adamantine on Descloizite.
Often found alongside austinite
Minerals reported to co-occur with austinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaZn(AsO₄)(OH)
- Mohs hardness
- 4
- Density
- 4.1-4.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, Radiating Clusters, Botryoidal, Crusts
- Cleavage
- None
- Fluorescence
- Bright Yellow-green Under SW UV
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Oxidized Zones of Arsenic-rich Base Metal Deposits
- Typical price
- $20-150 thumbnail to small cabinet specimens
Where rockhounds find austinite
Classic worldwide localities
- Gold Hill, Utah, USA
- Ojuela Mine, Mapimi, Mexico
- Tsumeb, Namibia
- Laurion, Greece
Field-hunting tip
Look in oxidized zones of arsenic-rich base metal deposits country — that is the host setting where austinite typically forms. If you start seeing conichalcite, adamite, limonite in float, you are in the right ground. Field specimens usually show a acicular, radiating clusters, botryoidal, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find austinite on the map
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