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, so 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, so 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, 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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