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.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Reederite-(Y)

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this reederite-(y)?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch reederite-(y) with a known reference. Reederite-(Y) sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Reederite-(Y) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Reederite-(Y) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-brown, brown.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: tabular crystals.

Often confused with

Reederite-(Y) vs. its common look-alikes — and how to tell them apart in the field.

How to tell apart: Luster reads vitreous on Reederite-(Y) and pearly on Dawsonite.

Compare →

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: Na₁₅Y₃(CO₃)₈(SO₄)₂F
Mohs hardness: 3.5
Density: 3.32 g/cm³
Colors: Yellow Yellow-brown Brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Hexagonal
Crystal habit: Tabular Crystals
Cleavage: None
Fluorescence: Bright Yellow Under SW UV
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $100-500 thumbnail

Where rockhounds find reederite-(y)

Classic worldwide localities

Mont Saint-Hilaire, Canada

Field-hunting tip

Look in alkaline igneous rocks country — that is the host setting where reederite-(y) typically forms. If you start seeing aegirine, microcline, sodalite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify reederite-(y)?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellow-brown, brown.

Where is reederite-(y) found?+

Notable localities include Mont Saint-Hilaire, Canada.

How much is reederite-(y) worth?+

Typical asking prices fall in the range of $100-500 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like reederite-(y)?+

Reederite-(Y) is most often confused with Carbocernaite, Dawsonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with reederite-(y)?+

Reederite-(Y) commonly co-occurs with Aegirine, Microcline, Sodalite, Analcime. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does reederite-(y) form in?+

Reederite-(Y) typically forms in alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is reederite-(y) used for?+

Reederite-(Y) is used in collector.

Find reederite-(y) on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.