Tondiite is a rare copper magnesium chloride hydroxide mineral found in the oxidation zones of copper-bearing deposits. It typically forms as small, dark green platy crystals or granular masses that can easily be mistaken for other members of the atacamite group.
Is this tondiite?
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 tondiite with a known reference. Tondiite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Tondiite leaves a light green streak.
- 3Read the lusterHold the specimen under a strong light. Tondiite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, blackish green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: platy crystals, granular aggregates.
Often confused with
Tondiite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Tondiite leaves light green, Atacamite leaves apple green; luster reads vitreous on Tondiite and adamantine to vitreous on Atacamite.
How to tell apart: Streak differs — Tondiite leaves light green, Paratacamite leaves apple green; luster reads vitreous on Tondiite and adamantine on Paratacamite.
How to tell apart: Streak differs — Tondiite leaves light green, Clinoatacamite leaves apple green.
Often found alongside tondiite
Minerals reported to co-occur with tondiite. 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
- 3
- Density
- 4.12 g/cm³
- Colors
- Streak
- Light Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Platy Crystals, Granular Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Copper Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find tondiite
Classic worldwide localities
- Tondi, Oravitsa, Romania
- Chile
- Arizona, USA
Field-hunting tip
Look in oxidized hydrothermal copper deposits country — that is the host setting where tondiite typically forms. If you start seeing quartz, goethite, chrysocolla in float, you are in the right ground. Field specimens usually show a platy crystals, granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find tondiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
