Mcgillite is a rare manganese silicate chloride typically found in metamorphosed ore deposits. Collectors look for its characteristic reddish-brown tabular crystals, though it is often found in massive form associated with other manganese minerals and sulfides.
Is this mcgillite?
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 mcgillite with a known reference. Mcgillite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly on cleavage surfaces.
- 4Match the color rangeCompare against the expected color range: dark pink, light pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, pseudo hexagonal.
Often confused with
Mcgillite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mcgillite
Minerals reported to co-occur with mcgillite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₈Si₆O₁₅(OH)₈Cl₂
- Mohs hardness
- 5
- Density
- 2.98 g/cm³
- Colors
- Dark pinkLight pink
- Streak
- Reddish white
- Luster
- Pearly on cleavage surfaces
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive, pseudo hexagonal
- Cleavage
- Good on {0001}; fair on {1011}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As open-space fracture fillings in a manganese-rich section of quartzite and argillite in a metamorphosed Pb{Zn orebody (Sullivan mine, Canada)
Where rockhounds find mcgillite
Classic worldwide localities
- Sullivan mine, Kimberley, Kootenay district, British Columbia, Canada
- Kyurazawa mine, Tochigi Prefecture, Japan
Field-hunting tip
Where it forms: As open-space fracture fillings in a manganese-rich section of quartzite and argillite in a metamorphosed Pb{Zn orebody (Sullivan mine, Canada). If you start seeing sphalerite, boulangerite, galena in float, you are in the right ground. Typical habit: massive, pseudo hexagonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mcgillite?+
Where is mcgillite found?+
What rocks look like mcgillite?+
What minerals are found with mcgillite?+
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Find mcgillite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
