Potassic-hastingsite is a complex iron-rich member of the amphibole supergroup, typically occurring as dark, opaque, prismatic crystals. It is most frequently found in alkali-rich igneous rocks like syenites or within contact-metamorphosed skarn zones.
Is this potassic-hastingsite?
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 potassic-hastingsite with a known reference. Potassic-hastingsite 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. Potassic-hastingsite leaves a grayish white streak.
- 3Read the lusterHold the specimen under a strong light. Potassic-hastingsite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Potassic-hastingsite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Potassic-hastingsite leaves grayish white, Hornblende leaves grayish-white.
How to tell apart: Streak differs — Potassic-hastingsite leaves grayish white, Hastingsite leaves white to light gray.
Often found alongside potassic-hastingsite
Minerals reported to co-occur with potassic-hastingsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KCa₂Fe²⁺₄Fe³⁺(Si₆Al₂O₂₂)(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.3-3.5 g/cm³
- Colors
- Streak
- Grayish White
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect in Two Directions
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks and Metamorphic Skarns
- Typical price
- $10-50 per specimen
Where rockhounds find potassic-hastingsite
Classic worldwide localities
- Canada
- Norway
- Russia
- USA
Field-hunting tip
Look in alkaline igneous rocks and metamorphic skarns country — that is the host setting where potassic-hastingsite typically forms. If you start seeing quartz, feldspar, biotite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify potassic-hastingsite?+
Where is potassic-hastingsite found?+
How much is potassic-hastingsite worth?+
What rocks look like potassic-hastingsite?+
What minerals are found with potassic-hastingsite?+
What kind of rock does potassic-hastingsite form in?+
What is potassic-hastingsite used for?+
Find potassic-hastingsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
