Muskoxite is a rare hydrated magnesium iron hydroxide mineral first identified in the Muskox Intrusion of Nunavut, Canada. It typically occurs as soft, brownish earthy crusts or fillings within serpentinized ultramafic rocks. Due to its obscure nature, it is primarily sought after by advanced systematic mineral collectors.
Is this muskoxite?
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 muskoxite with a known reference. Muskoxite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale orange-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark reddish brown, reddish brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: aggregates, anhedral grains.
Often confused with
Muskoxite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Goethite is the harder of the two (Mohs 5-5.5 vs. ~3); streak differs, so Muskoxite leaves pale orange-brown, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads vitreous on Muskoxite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
How to tell apart: Limonite is the harder of the two (Mohs 4-5.5 vs. ~3); streak differs, so Muskoxite leaves pale orange-brown, Limonite leaves yellowish-brown; luster reads vitreous on Muskoxite and submetallic to earthy on Limonite.
Often found alongside muskoxite
Minerals reported to co-occur with muskoxite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₇Fe₄(OH)₂₆·H₂O
- Mohs hardness
- ~3
- Density
- 3.10-3.20 g/cm³
- Streak
- Pale orange-brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Aggregates, anhedral grains
- Cleavage
- Perfect on {0001}, micaceous
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In thin veinlets in serpentinite from a layered ultramafic complex
Where rockhounds find muskoxite
Classic worldwide localities
- Muskox intrusion, Coppermine River area, Northwest Territories, Canada
Field-hunting tip
Where it forms: In thin veinlets in serpentinite from a layered ultramafic complex. If you start seeing lizardite, coalingite, mg–fe–mn oxides in float, you are in the right ground. Typical habit: aggregates, anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find muskoxite on the map
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