Fogoite-(Y) is an extremely rare silicate mineral discovered in the alkaline volcanic rocks of Fogo Island. It typically occurs as small, transparent prismatic crystals within cavities, often associated with other rare-earth bearing minerals.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

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Fogoite-(Y)

Hardness: 5-6
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this fogoite-(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 fogoite-(y) with a known reference. Fogoite-(Y) sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Fogoite-(Y) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fogoite-(Y) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brown, colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic crystals.

Often confused with

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

Often found alongside fogoite-(y)

Minerals reported to co-occur with fogoite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Na₃Ca₂Ce₂Zr(Si₂O₇)₂OF
Mohs hardness: 5-6
Density: 3.32 g/cm³
Colors: Yellow Brown Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Prismatic Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $100-500 per specimen

Where rockhounds find fogoite-(y)

Classic worldwide localities

Fogo Island, Cape Verde

Field-hunting tip

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

Common questions

How do you identify fogoite-(y)?+

Mohs hardness is 5-6. It typically shows a vitreous luster. The streak is white. Common colors include yellow, brown, colorless.

Where is fogoite-(y) found?+

Notable localities include Fogo Island, Cape Verde.

How much is fogoite-(y) worth?+

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

What rocks look like fogoite-(y)?+

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

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

Fogoite-(Y) commonly co-occurs with Nepheline, Aegirine, Titanite. Spotting any of these in float or country rock is a useful trip signal.

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

Fogoite-(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 fogoite-(y) used for?+

Fogoite-(Y) is used in collector.

Find fogoite-(y) on the map

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