Humite is a rare member of the humite group typically found in contact metamorphosed carbonate rocks. It is most easily recognized by its distinct orange-yellow to brownish-red hues and vitreous luster in granular or crystalline aggregates.
Is this humite?
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 humite with a known reference. Humite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, brown, white, dark orange.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: granular, compact masses, or small rounded orthorhombic crystals.
Often confused with
Humite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside humite
Minerals reported to co-occur with humite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₇(SiO₄)₃F₂
- Mohs hardness
- 6
- Density
- 3.20-3.32 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Granular, compact masses, or small rounded orthorhombic crystals
- Cleavage
- {100}, poor
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- Typically in contact metamorphic zones in limestones and dolostones associated with felsic, or more rarely, alkalic plutonic rocks, especially where metasomatism has introduced Fe, B, and F
Where rockhounds find humite
Classic worldwide localities
- Tilly Foster mine, Brewster, Putnam Co., New York, and at Franklin, Sussex Co., New Jersey, USA
- Monte Somma and Vesuvius, Campania, Italy
- Lohja, Sillböle, and Hermala, Finland
- Norberg area, and at the Ladu mine, Persberg, Värmland, Sweden
- Sorfinnset, Glomfjord, Norway
- Llanos de Juanar, Málaga Province, Spain
Field-hunting tip
Where it forms: Typically in contact metamorphic zones in limestones and dolostones associated with felsic, or more rarely, alkalic plutonic rocks, especially where metasomatism has introduced Fe, B, and F. If you start seeing grossular, wollastonite, forsterite in float, you are in the right ground. Typical habit: granular, compact masses, or small rounded orthorhombic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find humite on the map
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