Nantokite is a rare copper chloride mineral that typically forms as an alteration product in copper ore deposits. It is highly sensitive to humidity and will rapidly oxidize and hydrate to form green copper minerals like atacamite when exposed to air.
Is this nantokite?
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 nantokite with a known reference. Nantokite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless, white, grayish, green.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive.
Often confused with
Nantokite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside nantokite
Minerals reported to co-occur with nantokite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuCl
- Mohs hardness
- 2.5
- Density
- 3.93-4.3 g/cm³
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Cubic
- Crystal habit
- Massive
- Cleavage
- Good on {001}; good on {010}; good on {100}
- Rarity
- Rare
- Uses
- Collector, Geological study
- Host rock
- A secondary mineral in hydrothermal copper-bearing deposits; rarely in volcanic sublimates
Where rockhounds find nantokite
Classic worldwide localities
- Bisbee, Cochise County, Arizona, and in the Steeple Rock district, Grant Co., New Mexico, USA
- Carmen Bajo mine, Pintada Mountain, near Nantoko, Copiapó district, Atacama, Chile
- Broken Hill, New South Wales, and at the Wewak, Magpie, and Great Australia mines, Cloncurrie, Queensland, Australia
- Malanjkhand copper deposit, north of Durg, Madhya Pradesh, India
- Tolbachik volcano, Kamchatka Peninsula, Russia
- Dzhezkazgan, Kazakhstan
Field-hunting tip
Where it forms: A secondary mineral in hydrothermal copper-bearing deposits; rarely in volcanic sublimates. If you start seeing cuprite, copper, atacamite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nantokite?+
Where is nantokite found?+
Is nantokite safe to handle?+
What rocks look like nantokite?+
What minerals are found with nantokite?+
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Find nantokite on the map
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