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 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mcgillite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mcgillite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: reddish-brown, pinkish-red.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular crystals, massive.
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)₁₀Cl₂
- Mohs hardness
- 5-6
- Density
- 3.31 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Tabular Crystals, Massive
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Sedimentary Ore Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find mcgillite
Classic worldwide localities
- Sullivan Mine, British Columbia, Canada
- Sterling Hill, New Jersey, USA
Field-hunting tip
Look in metamorphosed sedimentary ore deposits country — that is the host setting where mcgillite typically forms. If you start seeing calcite, sphalerite, galena in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find mcgillite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
