Chondrodite is a member of the Humite group, frequently occurring as yellow to orange grains or small crystals embedded in contact-metamorphosed limestones. Collectors prize it for its strong fluorescence and distinct color, often seeking specimens from classic localities like the Franklin mining district.
Is this chondrodite?
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 chondrodite with a known reference. Chondrodite sits at Mohs 6-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: yellow, orange, brownish white, reddish white, greenish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: crystalline, massive.
Often confused with
Chondrodite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Chondrodite leaves gray, Spessartine leaves white.
How to tell apart: Zircon is the harder of the two (Mohs 7.5 vs. 6-6.5); streak differs, so Chondrodite leaves gray, Zircon leaves white.
How to tell apart: Streak differs, so Chondrodite leaves gray, Clinohumite leaves white.
Often found alongside chondrodite
Minerals reported to co-occur with chondrodite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₅(SiO₄)₂F₂
- Mohs hardness
- 6-6.5
- Density
- 3.16-3.26 g/cm³
- Streak
- Gray
- Luster
- Vitreous to resinous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Crystalline, massive
- Cleavage
- {100} indistinct; parting on {001}
- Fluorescence
- Orange yellow under SW UV; orange under LW UV
- Rarity
- Uncommon
- Uses
- Collector, Gemstone
- Host rock
- In contact metamorphic zones, in limestones and dolostones, associated with felsic to alkalic plutonic rocks, especially with Fe-B-F metasomatism; in a carbonatite
Where rockhounds find chondrodite
3 mapped spotsClassic worldwide localities
- Tilly Foster mine, Brewster, Putnam Co., and Amity, Orange Co., New York, USA
- Franklin and Sparta, Sussex Co., New Jersey, USA
- Johnson Camp, Cochise Co., and the Lakeshore mine, Pinal Co., Arizona, USA
- Crestmore, Riverside Co., California, USA
- Pargas, Hangelby, and Sibbo, Finland
- Kafveltorp, near Kopparberg, Sweden
Field-hunting tip
Where it forms: In contact metamorphic zones, in limestones and dolostones, associated with felsic to alkalic plutonic rocks, especially with Fe-B-F metasomatism; in a carbonatite. If you start seeing phlogopite, spinel, magnetite in float, you are in the right ground. Typical habit: crystalline, massive. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Jersey, New York. Start trip planning there.
Common questions
How do you identify chondrodite?+
Where is chondrodite found?+
Can I find chondrodite in the United States?+
What rocks look like chondrodite?+
What minerals are found with chondrodite?+
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Find chondrodite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
