Aenigmatite is a complex sodium-iron-titanium silicate typically found in peralkaline igneous rocks. It is most easily identified by its dark, often black, prismatic crystals and high density compared to common amphiboles. Collectors usually hunt for it in syenite pegmatites or nepheline syenites where it occurs as a primary mineral.
Is this aenigmatite?
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 aenigmatite with a known reference. Aenigmatite sits at Mohs 5.5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Aenigmatite leaves a reddish-brown streak.
- 3Read the lusterHold the specimen under a strong light. Aenigmatite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Aenigmatite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Aenigmatite leaves reddish-brown, Arfvedsonite leaves grey to bluish-grey.
How to tell apart: Streak differs — Aenigmatite leaves reddish-brown, Hornblende leaves grayish-white.
How to tell apart: Streak differs — Aenigmatite leaves reddish-brown, Augite leaves grayish white.
Often found alongside aenigmatite
Minerals reported to co-occur with aenigmatite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂Fe²⁺₅TiSi₆O₂₀
- Mohs hardness
- 5.5-6
- Density
- 3.7-3.8 g/cm³
- Colors
- Streak
- Reddish-brown
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Prismatic Crystals, Massive, Granular
- Cleavage
- Distinct in Two Directions
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research
- Host rock
- Alkaline Igneous Rocks and Pegmatites
- Typical price
- $20-150 per specimen
Where rockhounds find aenigmatite
Classic worldwide localities
- Greenland
- Scotland
- Norway
- Canada
- Madagascar
Field-hunting tip
Look in alkaline igneous rocks and pegmatites country — that is the host setting where aenigmatite typically forms. If you start seeing microcline, albite, nepheline 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 aenigmatite?+
Where is aenigmatite found?+
How much is aenigmatite worth?+
What rocks look like aenigmatite?+
What minerals are found with aenigmatite?+
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Find aenigmatite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
