Magnesio-ferri-hornblende is a member of the complex amphibole group found in a variety of igneous and metamorphic environments. Collectors typically look for its dark, elongated prismatic crystals which are best identified through professional analytical testing due to their similarity to other hornblende-series members.
Is this magnesio-ferri-hornblende?
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-ferri-hornblende with a known reference. Magnesio-ferri-hornblende 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-ferri-hornblende leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Magnesio-ferri-hornblende typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Magnesio-ferri-hornblende vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Magnesio-ferri-hornblende leaves white, Hornblende leaves grayish-white.
How to tell apart: Luster reads vitreous on Magnesio-ferri-hornblende and vitreous to silky on Actinolite.
How to tell apart: Streak differs — Magnesio-ferri-hornblende leaves white, Ferro-hornblende leaves grayish white.
Often found alongside magnesio-ferri-hornblende
Minerals reported to co-occur with magnesio-ferri-hornblende. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂(Mg₃Fe³⁺Fe²⁺)Si₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.1-3.4 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect Prismatic At 56 and 124 Degrees
- Rarity
- Common
- Uses
- Collector, Petrological Research
- Host rock
- Igneous and Metamorphic Rocks
- Typical price
- $10-50 per specimen
Where rockhounds find magnesio-ferri-hornblende
Classic worldwide localities
- Norway
- Sweden
- Finland
- USA
- Canada
Field-hunting tip
Look in igneous and metamorphic rocks country — that is the host setting where magnesio-ferri-hornblende 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
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Find magnesio-ferri-hornblende on the map
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