Ferro-pargasite is a member of the amphibole supergroup, occurring primarily as a dark-colored mineral in calc-silicate metamorphic environments. It typically forms stout, short-prismatic crystals and is often indistinguishable from other amphiboles without specialized chemical testing.
Is this ferro-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 ferro-pargasite with a known reference. Ferro-pargasite 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. Streak: white to pale gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black, dark green, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, granular, massive.
Often confused with
Ferro-pargasite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferro-pargasite leaves white to pale gray, Hornblende leaves grayish-white.
How to tell apart: Streak differs, so Ferro-pargasite leaves white to pale gray, Hastingsite leaves greenish gray.
Often found alongside ferro-pargasite
Minerals reported to co-occur with ferro-pargasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂Fe²⁺₄Al(Si₆Al₂)O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.44 g/cm³
- Streak
- White to pale gray
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, granular, massive
- Cleavage
- Perfect on {110}, with intersections at ~56° and ~124°; partings on {100}, {001}
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- In an amphibolite facies metamorphosed banded iron formation
Where rockhounds find ferro-pargasite
Classic worldwide localities
- Flowerdale, near Gairloch, Scotland
Field-hunting tip
Where it forms: In an amphibolite facies metamorphosed banded iron formation. If you start seeing grunerite, almandine, biotite in float, you are in the right ground. Typical habit: prismatic crystals, granular, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferro-pargasite?+
Where is ferro-pargasite found?+
What rocks look like ferro-pargasite?+
What minerals are found with ferro-pargasite?+
What kind of rock does ferro-pargasite form in?+
What is ferro-pargasite used for?+
Find ferro-pargasite on the map
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