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. Streak: dark green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 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, so Potassic-hastingsite leaves dark green, Hornblende leaves grayish-white.
How to tell apart: Streak differs, so Potassic-hastingsite leaves dark green, Hastingsite leaves greenish gray.
How to tell apart: Streak differs, so Potassic-hastingsite leaves dark green, Magnesio-hastingsite leaves grayish white.
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
- Dark green
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- Perfect in two directions
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- alkaline igneous rocks and metamorphic skarns
Where rockhounds find potassic-hastingsite
Classic worldwide localities
- Danailingou, Tongxing town, Keshiketeng Banner, Inner Mongolia, China
Field-hunting tip
Where it forms: alkaline igneous rocks and metamorphic skarns. If you start seeing quartz, feldspar, biotite 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 potassic-hastingsite?+
Where is potassic-hastingsite found?+
What rocks look like potassic-hastingsite?+
What minerals are found with potassic-hastingsite?+
What kind of rock does potassic-hastingsite form in?+
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Find potassic-hastingsite on the map
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