Foggite is a rare phosphate mineral primarily known from the Big Fish River area in the Yukon. It typically occurs as small, delicate, white to colorless acicular or lath-like crystals associated with other rare secondary phosphates in vugs.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Foggite

Hardness: 3-4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this foggite?

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 foggite with a known reference. Foggite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Foggite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Foggite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular to lath-like crystals.

Often confused with

Foggite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Veszelyite

Mohs 3.5-4

How to tell apart: Streak differs, so Foggite leaves white, Veszelyite leaves light green.

Often found alongside foggite

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

All properties

Chemical formula: CaAl(PO₄)(OH)₂·H₂O
Mohs hardness: 3-4
Density: 2.81 g/cm³
Colors: White Colorless Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Acicular to Lath-like Crystals
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Collector
Host rock: Phosphate-rich Sedimentary Concretions in Iron Formation
Typical price: $50-300 for high-quality micro-specimens

Where rockhounds find foggite

Classic worldwide localities

Big Fish River, Yukon, Canada
Rapid Creek, Yukon, Canada

Field-hunting tip

Look in phosphate-rich sedimentary concretions in iron formation country, the host setting where foggite typically forms. If you start seeing montgomeryite, englishite, crandallite in float, you are in the right ground. Field specimens usually show a acicular to lath-like crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify foggite?+

Mohs hardness is 3-4. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pale yellow.

Where is foggite found?+

Notable localities include Big Fish River, Yukon, Canada; Rapid Creek, Yukon, Canada.

How much is foggite worth?+

Typical asking prices fall in the range of $50-300 for high-quality micro-specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like foggite?+

Foggite is most often confused with Veszelyite, Montgomeryite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with foggite?+

Foggite commonly co-occurs with Montgomeryite, Englishite, Crandallite, Wardite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does foggite form in?+

Foggite typically forms in phosphate-rich sedimentary concretions in iron formation. Working float back to the host body is the standard way to chase a fresh occurrence.

What is foggite used for?+

Foggite is used in collector.

Find foggite on the map

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