Potassic-magnesio-arfvedsonite is a rare member of the amphibole supergroup, typically found in undersaturated alkaline igneous complexes. It is visually similar to other dark amphiboles and is best distinguished through micro-analysis or its specific paragenetic occurrence in syenitic rocks.
Is this potassic-magnesio-arfvedsonite?
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 potassic-magnesio-arfvedsonite with a known reference. Potassic-magnesio-arfvedsonite 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. Potassic-magnesio-arfvedsonite leaves a grey to pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Potassic-magnesio-arfvedsonite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, dark green, dark blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, acicular, massive.
Often confused with
Potassic-magnesio-arfvedsonite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Potassic-magnesio-arfvedsonite leaves grey to pale blue, Arfvedsonite leaves grey to bluish-grey.
How to tell apart: Streak differs — Potassic-magnesio-arfvedsonite leaves grey to pale blue, Riebeckite leaves blue-gray.
How to tell apart: Streak differs — Potassic-magnesio-arfvedsonite leaves grey to pale blue, Hornblende leaves grayish-white.
Often found alongside potassic-magnesio-arfvedsonite
Minerals reported to co-occur with potassic-magnesio-arfvedsonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(Na₂)(Mg₄Fe³⁺)Si₈O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.1-3.5 g/cm³
- Colors
- Streak
- Grey to Pale Blue
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Acicular, Massive
- Cleavage
- Perfect in Two Directions
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Alkaline Igneous Rocks, Syenites, Pegmatites
- Typical price
- $20-150 per specimen
Where rockhounds find potassic-magnesio-arfvedsonite
Classic worldwide localities
- Kola Peninsula, Russia
- Mont Saint-Hilaire, Canada
- Greenland
- Norway
Field-hunting tip
Look in alkaline igneous rocks, syenites, pegmatites country — that is the host setting where potassic-magnesio-arfvedsonite typically forms. If you start seeing nepheline, aegirine, microcline in float, you are in the right ground. Field specimens usually show a prismatic crystals, acicular, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify potassic-magnesio-arfvedsonite?+
Where is potassic-magnesio-arfvedsonite found?+
How much is potassic-magnesio-arfvedsonite worth?+
What rocks look like potassic-magnesio-arfvedsonite?+
What minerals are found with potassic-magnesio-arfvedsonite?+
What kind of rock does potassic-magnesio-arfvedsonite form in?+
What is potassic-magnesio-arfvedsonite used for?+
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