Magnesio-fluoro-hastingsite is a rare member of the complex amphibole group, typically identified by its dark, prismatic crystals found in metamorphic environments. It is often indistinguishable from other dark amphiboles without advanced chemical analysis like electron microprobe testing.
Is this magnesio-fluoro-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 magnesio-fluoro-hastingsite with a known reference. Magnesio-fluoro-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. Magnesio-fluoro-hastingsite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Magnesio-fluoro-hastingsite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, black, brownish-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Magnesio-fluoro-hastingsite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Magnesio-fluoro-hastingsite leaves white, Hastingsite leaves white to light gray.
How to tell apart: Streak differs — Magnesio-fluoro-hastingsite leaves white, Hornblende leaves grayish-white.
How to tell apart: Streak differs — Magnesio-fluoro-hastingsite leaves white, Magnesio-hastingsite leaves grayish white.
Often found alongside magnesio-fluoro-hastingsite
Minerals reported to co-occur with magnesio-fluoro-hastingsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂Mg₄Fe³⁺(Al₂Si₆O₂₂)F₂
- Mohs hardness
- 5-6
- Density
- 3.3-3.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Massive, Granular
- Cleavage
- Perfect On {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Rocks, Skarns
- Typical price
- $20-100 per specimen depending on size and quality
Where rockhounds find magnesio-fluoro-hastingsite
Classic worldwide localities
- Canada
- Italy
- Norway
- USA
Field-hunting tip
Look in metamorphic rocks, skarns country — that is the host setting where magnesio-fluoro-hastingsite typically forms. If you start seeing calcite, diopside, phlogopite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify magnesio-fluoro-hastingsite?+
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Find magnesio-fluoro-hastingsite on the map
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