Mattagamite is a rare cobalt telluride mineral that typically appears as metallic, white to gray grains within sulfide ore deposits. It is best identified through microscopic analysis and electron microprobe testing, as it rarely forms distinct macroscopic crystals. It is primarily sought after by advanced mineral collectors of rare telluride species.
Is this mattagamite?
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 mattagamite with a known reference. Mattagamite sits at Mohs 5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: violet, violet gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: inclusions, twinning common.
Often confused with
Mattagamite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Mattagamite is noticeably harder (Mohs 5.5 vs. 2.5); streak differs, so Mattagamite leaves gray, Froodite leaves black.
How to tell apart: Mattagamite is noticeably harder (Mohs 5.5 vs. 1-1.5); streak differs, so Mattagamite leaves gray, Melonite leaves dark gray.
How to tell apart: Mattagamite is noticeably harder (Mohs 5.5 vs. 1.5-2); streak differs, so Mattagamite leaves gray, Tellurobismuthite leaves pale lead-gray.
Often found alongside mattagamite
Minerals reported to co-occur with mattagamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoTe₂
- Mohs hardness
- 5.5
- Density
- 8.00 g/cm³
- Colors
- VioletViolet gray
- Streak
- Gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Inclusions, twinning common
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a small telluride zone in a massive zinc-rich stratiform deposit in Archaen volcanics (Mattagami Lake mine, Canada)
Where rockhounds find mattagamite
Classic worldwide localities
- Mattagami Lake mine, near Matagami, Quebec, Canada (type locality)
- Zhena-Tyube deposit, Kazakhstan
- Kuusamo schist belt, northeastern Finland
Field-hunting tip
Where it forms: In a small telluride zone in a massive zinc-rich stratiform deposit in Archaen volcanics (Mattagami Lake mine, Canada). If you start seeing frohbergite, altaite, pyrrhotite in float, you are in the right ground. Typical habit: inclusions, twinning common. Train your eye for that shape before scanning the outcrop.
Common questions
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Is mattagamite safe to handle?+
What rocks look like mattagamite?+
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Find mattagamite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
