Fluoro-pargasite is a member of the calcic amphibole group, distinguished by dominant fluorine in the hydroxyl site. Collectors usually find it as deep green, stout prismatic crystals often embedded in crystalline limestone or contact metamorphic skarn rocks.
Is this fluoro-pargasite?
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 fluoro-pargasite with a known reference. Fluoro-pargasite 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: gray to greenish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Fluoro-pargasite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Fluoro-pargasite leaves gray to greenish gray, Hornblende leaves grayish-white.
How to tell apart: Streak differs, so Fluoro-pargasite leaves gray to greenish gray, Edenite leaves white.
How to tell apart: Streak differs, so Fluoro-pargasite leaves gray to greenish gray, Hastingsite leaves greenish gray.
Often found alongside fluoro-pargasite
Minerals reported to co-occur with fluoro-pargasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂Mg₄Al(Si₆Al₂)O₂₂F₂
- Mohs hardness
- ~6
- Density
- 3.18 g/cm³
- Colors
- Streak
- Gray to greenish gray
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- Perfect on {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In granulite facies metacarbonate rocks
Where rockhounds find fluoro-pargasite
Classic worldwide localities
- Franklin Marble, at Edenville, Orange County, and from Russell, St. Lawrence County, and Monroe, Orange County, New York, USA
Field-hunting tip
Where it forms: In granulite facies metacarbonate rocks. If you start seeing calcite, actinolite, titanite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fluoro-pargasite?+
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Find fluoro-pargasite on the map
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