Haydeeite is a rare copper-magnesium chloride mineral occurring in the oxidized zones of copper deposits. It is typically identified by its distinct dark green platy crystals found in association with other copper secondary minerals.
Is this haydeeite?
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 haydeeite with a known reference. Haydeeite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: bright greenish-blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: bluish green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: acicular.
Often confused with
Haydeeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Atacamite is the harder of the two (Mohs 3-3.5 vs. 2); streak differs, so Haydeeite leaves bright greenish-blue, Atacamite leaves apple-green; luster reads vitreous on Haydeeite and adamantine to vitreous on Atacamite.
How to tell apart: Paratacamite is the harder of the two (Mohs 3 vs. 2); streak differs, so Haydeeite leaves bright greenish-blue, Paratacamite leaves green.
How to tell apart: Botallackite is the harder of the two (Mohs 3 vs. 2); streak differs, so Haydeeite leaves bright greenish-blue, Botallackite leaves light green.
Often found alongside haydeeite
Minerals reported to co-occur with haydeeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₃Mg(OH)₆Cl₂
- Mohs hardness
- 2
- Density
- 3.27 g/cm³
- Colors
- Streak
- Bright greenish-blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Acicular
- Cleavage
- Perfect {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Atacamite group
Where rockhounds find haydeeite
Classic worldwide localities
- Haydee mine, western border of the southern end of Salar Grande, 110 km SE of Iquique, Atacama Desert, Tarapacá Province, northern Chile
Field-hunting tip
Where it forms: Atacamite group. If you start seeing gypsum, halite, cuprite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify haydeeite?+
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Find haydeeite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
