Ajoite is a stunning, rare copper silicate mineral highly sought after by collectors for its vibrant blue-green color. It most frequently appears as delicate, fibrous sprays or tufts included within clear quartz crystals, especially those from the Messina district. It is a secondary mineral formed by the oxidation of copper deposits and is typically found in small amounts.
Is this ajoite?
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 ajoite with a known reference. Ajoite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: bluish green, blue green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: lath, massive, platy.
Often confused with
Ajoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Papagoite is the harder of the two (Mohs 5-5.5 vs. 3.5); streak differs, so Ajoite leaves greenish white, Papagoite leaves light blue.
How to tell apart: Planerite is the harder of the two (Mohs 5 vs. 3.5); streak differs, so Ajoite leaves greenish white, Planerite leaves blue white; luster reads vitreous on Ajoite and dull, chalky to earthy on Planerite.
How to tell apart: Streak differs, so Ajoite leaves greenish white, Chrysocolla leaves white when pure.
Often found alongside ajoite
Minerals reported to co-occur with ajoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₃Cu₂₀Al₃Si₂₉O₇₆(OH)₁₆·8H₂O
- Mohs hardness
- 3.5
- Density
- 2.96 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Lath, massive, platy
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector, Metaphysical specimen
- Host rock
- In oxidized copper-rich base-metal deposits
Where rockhounds find ajoite
Classic worldwide localities
- New Cornelia mine, Ajo, Pima Co., Arizona, USA
- Moon Anchor mine and Potter-Cramer property, near Wickenburg, Maricopa Co., Arizona, USA
- A prospect in Copper Creek, Pinal Co., Arizona, USA
- Munihuaza, near Alamos, Sonora, Mexico
- Messina, Transvaal, South Africa
Field-hunting tip
Where it forms: In oxidized copper-rich base-metal deposits. If you start seeing shattuckite, conichalcite, quartz in float, you are in the right ground. Typical habit: lath, massive, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ajoite?+
Where is ajoite found?+
Is ajoite safe to handle?+
What rocks look like ajoite?+
What minerals are found with ajoite?+
What kind of rock does ajoite form in?+
What is ajoite used for?+
Find ajoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
