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, 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
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