Magnesio-hastingsite is a complex member of the amphibole supergroup, typically found in high-grade metamorphic environments and alkaline igneous rocks. Collectors often identify it by its dark, opaque to translucent prismatic habit and typical occurrence alongside calcium-rich silicates in skarn deposits.
Is this magnesio-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-hastingsite with a known reference. Magnesio-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: grayish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Magnesio-hastingsite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Magnesio-hastingsite leaves grayish white, Hornblende leaves grayish-white.
How to tell apart: Streak differs, so Magnesio-hastingsite leaves grayish white, Hastingsite leaves greenish gray.
How to tell apart: Streak differs, so Magnesio-hastingsite leaves grayish white, Edenite leaves white.
Often found alongside magnesio-hastingsite
Minerals reported to co-occur with magnesio-hastingsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂(Mg₄Fe³⁺)(Si₆Al₂)O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.18-3.22 g/cm³
- Colors
- Streak
- Grayish white
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, massive, granular
- Cleavage
- Perfect on {110}, with intersections at ~56° and ~124°; partings on {001}, {100}
- Rarity
- Uncommon
- Uses
- Collector, Scientific research
- Host rock
- In alkalic basalts; in andesites, latites, tephrites, and their tuffs; in carbonatites
Where rockhounds find magnesio-hastingsite
Classic worldwide localities
- Iron Hill, Gunnison Co., Colorado, USA
- Untertiefenbach, Austria
- Březno nad Labem (Grosspriesen), Czech Republic
- Radersberg, Eifel district, Germany
- Gillinge and Långban, Värmland, Sweden
- Khibiny massif, Kola Peninsula, Russia
Field-hunting tip
Where it forms: In alkalic basalts; in andesites, latites, tephrites, and their tuffs; in carbonatites. If you start seeing olivine, plagioclase, pyroxenes in float, you are in the right ground. Typical habit: prismatic crystals, massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify magnesio-hastingsite?+
Where is magnesio-hastingsite found?+
What rocks look like magnesio-hastingsite?+
What minerals are found with magnesio-hastingsite?+
What kind of rock does magnesio-hastingsite form in?+
What is magnesio-hastingsite used for?+
Find magnesio-hastingsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
