Pargasite is a magnesium-rich member of the calcic amphibole group, typically found in regionally metamorphosed limestone and skarn deposits. It often forms distinct, stocky prismatic crystals that can be difficult to distinguish from other dark amphiboles without chemical analysis. Collectors prize it for its association with secondary minerals like spinel and phlogopite in contact metamorphic zones.
Is this 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 pargasite with a known reference. 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.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark green, bluish green, brown, grayish black, light brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular.
Often confused with
Pargasite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside pargasite
Minerals reported to co-occur with pargasite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂(Mg₄Al)(Si₆Al₂)O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.04-3.17 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular
- Cleavage
- Perfect on {110}, intersecting at 56° and 124°; partings on {100}, {001}
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- A common component of hornblendes in skarns metamorphosed from siliceous limestones; schists and amphibolites; also from andesitic volcanic and altered ultramafic rocks
Where rockhounds find pargasite
Classic worldwide localities
- Franklin, Sussex Co., New Jersey, USA
- Parainen (Pargas), Finland
- Långban, Värmland, Sweden
- Saualpe, Carinthia, Austria
- Vesuvius, Campania, Italy
- Wolfe Lake, Ontario, Canada
Field-hunting tip
Where it forms: A common component of hornblendes in skarns metamorphosed from siliceous limestones; schists and amphibolites; also from andesitic volcanic and altered ultramafic rocks. If you start seeing diopside, phlogopite, corundum in float, you are in the right ground. Typical habit: tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pargasite?+
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What rocks look like pargasite?+
What minerals are found with pargasite?+
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Find pargasite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
