Cobaltaustinite is a rare arsenic-bearing mineral known for its vibrant green color caused by cobalt substitution. It typically occurs as small, crusty, or botryoidal growths in oxidized polymetallic ore deposits. Collectors prize it primarily for its distinct color and association with other rare secondary arsenate minerals.
Is this cobaltaustinite?
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 cobaltaustinite with a known reference. Cobaltaustinite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Cobaltaustinite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Cobaltaustinite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: bright green, yellowish-green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crusts, botryoidal aggregates, acicular crystals.
Often confused with
Cobaltaustinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cobaltaustinite leaves pale green, Austinite leaves white; luster reads vitreous on Cobaltaustinite and subadamantine to silky on Austinite.
How to tell apart: Streak differs, so Cobaltaustinite leaves pale green, Conichalcite leaves light green.
Often found alongside cobaltaustinite
Minerals reported to co-occur with cobaltaustinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCo(AsO₄)(OH)
- Mohs hardness
- 4.5
- Density
- 4.45 g/cm³
- Streak
- Pale Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Crusts, Botryoidal Aggregates, Acicular Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Hydrothermal Base-metal Deposits
Where rockhounds find cobaltaustinite
Classic worldwide localities
- Dome Rock copper mine, about 40 km northwest of Mingary, South Australia
Field-hunting tip
Look in oxidized zones of hydrothermal base-metal deposits country, the host setting where cobaltaustinite typically forms. If you start seeing arsenates, limonite, malachite in float, you are in the right ground. Field specimens usually show a crusts, botryoidal aggregates, acicular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cobaltaustinite?+
Where is cobaltaustinite found?+
Is cobaltaustinite safe to handle?+
What rocks look like cobaltaustinite?+
What minerals are found with cobaltaustinite?+
What kind of rock does cobaltaustinite form in?+
What is cobaltaustinite used for?+
Find cobaltaustinite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
