Ferri-fluoro-katophorite is a rare member of the complex amphibole group, typically found in alkaline igneous environments. Collectors identify it by its dark, prismatic habit and specific associations with nepheline syenite assemblages. Due to its chemical complexity, professional analysis is often required for definitive identification compared to other members of the amphibole supergroup.
Is this ferri-fluoro-katophorite?
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-fluoro-katophorite with a known reference. Ferri-fluoro-katophorite 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. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: greenish gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, acicular aggregates, massive.
Often confused with
Ferri-fluoro-katophorite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferri-fluoro-katophorite leaves gray, Hornblende leaves grayish-white.
How to tell apart: Streak differs, so Ferri-fluoro-katophorite leaves gray, Arfvedsonite leaves deep bluish gray, gray-green.
How to tell apart: Streak differs, so Ferri-fluoro-katophorite leaves gray, Riebeckite leaves greenish brown.
Often found alongside ferri-fluoro-katophorite
Minerals reported to co-occur with ferri-fluoro-katophorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(NaCa)(Mg₄Fe)(Si₇Al)O₂₂F₂
- Mohs hardness
- 5-6
- Density
- 3.19 g/cm³
- Colors
- Streak
- Gray
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, acicular aggregates, massive
- Cleavage
- Perfect on {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In carbonatite dikes
Where rockhounds find ferri-fluoro-katophorite
Classic worldwide localities
- Bear Lake diggings, 8.4 km west of Tory Hill, Monmouth Township, Bancroft area, Ontario, Canada
Field-hunting tip
Where it forms: In carbonatite dikes. If you start seeing phlogopite, microcline perthite, titanite in float, you are in the right ground. Typical habit: prismatic crystals, acicular aggregates, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferri-fluoro-katophorite?+
Where is ferri-fluoro-katophorite found?+
What rocks look like ferri-fluoro-katophorite?+
What minerals are found with ferri-fluoro-katophorite?+
What kind of rock does ferri-fluoro-katophorite form in?+
What is ferri-fluoro-katophorite used for?+
Find ferri-fluoro-katophorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
