Oxo-magnesio-hastingsite is a rare member of the calcic amphibole group, typically identified through sophisticated mineralogical analysis. It occurs primarily as prismatic crystals within alkaline igneous complexes. Collectors look for these dark, lustrous crystals in environments associated with iron-rich metamorphic or metasomatic processes.
Is this oxo-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 oxo-magnesio-hastingsite with a known reference. Oxo-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. Oxo-magnesio-hastingsite leaves a pale gray streak.
- 3Read the lusterHold the specimen under a strong light. Oxo-magnesio-hastingsite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, dark green, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Oxo-magnesio-hastingsite vs. its common look-alikes — and how to tell them apart in the field.

How to tell apart: Streak differs — Oxo-magnesio-hastingsite leaves pale gray, Hastingsite leaves white to light gray.

How to tell apart: Streak differs — Oxo-magnesio-hastingsite leaves pale gray, Hornblende leaves grayish-white.

How to tell apart: Streak differs — Oxo-magnesio-hastingsite leaves pale gray, Magnesio-hastingsite leaves grayish white.
Often found alongside oxo-magnesio-hastingsite
Minerals reported to co-occur with oxo-magnesio-hastingsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCa₂(Fe₃⁺₅)Si₆Al₂O₂₂(O)₂
- Mohs hardness
- 5-6
- Density
- 3.35-3.45 g/cm³
- Colors
- Streak
- Pale Gray
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect On {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks
- Typical price
- $20-100 per specimen
Where rockhounds find oxo-magnesio-hastingsite
Classic worldwide localities
- Finland
- Russia
- Sweden
Field-hunting tip
Look in alkaline igneous rocks country — that is the host setting where oxo-magnesio-hastingsite typically forms. If you start seeing plagioclase, quartz, 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.




