Reederite-(Y) is an exceptionally rare carbonate mineral primarily found in the complex alkaline rocks of Mont Saint-Hilaire. It is best identified by its distinct hexagonal tabular habit and characteristic bright yellow fluorescence under short-wave ultraviolet light.
Is this reederite-(y)?
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 reederite-(y) with a known reference. Reederite-(Y) sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow, orange brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: blocky, granular.
Often confused with
Reederite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside reederite-(y)
Minerals reported to co-occur with reederite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Na,Mn)₁₅Y₂(CO₃)₉(SO₃F)Cl
- Mohs hardness
- 3-3.5
- Density
- 2.91 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Blocky, granular
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare mineral in a sodalite xenolith in syenite in an intrusive alkalic gabbro-syenite complex
Where rockhounds find reederite-(y)
Classic worldwide localities
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Where it forms: A very rare mineral in a sodalite xenolith in syenite in an intrusive alkalic gabbro-syenite complex. If you start seeing trona, shortite, petersenite- in float, you are in the right ground. Typical habit: blocky, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify reederite-(y)?+
Where is reederite-(y) found?+
What rocks look like reederite-(y)?+
What minerals are found with reederite-(y)?+
What kind of rock does reederite-(y) form in?+
What is reederite-(y) used for?+
Find reederite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
