Ferri-obertiite is a rare member of the amphibole supergroup, typically found in highly alkaline igneous environments. It usually appears as small, dark-colored prismatic crystals that are difficult to distinguish from other amphiboles without specialized chemical analysis like electron microprobe testing.
Is this ferri-obertiite?
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 ferri-obertiite with a known reference. Ferri-obertiite 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. Ferri-obertiite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ferri-obertiite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, dark brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Ferri-obertiite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferri-obertiite
Minerals reported to co-occur with ferri-obertiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(Na₂)(Mg₃Fe³⁺Ti)Si₈O₂₂O₂
- Mohs hardness
- 5-6
- Density
- 3.24 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Perfect Prismatic
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find ferri-obertiite
Classic worldwide localities
- Mont Saint-Hilaire, Canada
- Khibiny Massif, Russia
Field-hunting tip
Look in alkaline igneous rocks country — that is the host setting where ferri-obertiite typically forms. If you start seeing aegirine, nepheline, microcline 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
How do you identify ferri-obertiite?+
Where is ferri-obertiite found?+
How much is ferri-obertiite worth?+
What rocks look like ferri-obertiite?+
What minerals are found with ferri-obertiite?+
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Find ferri-obertiite on the map
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