Johnsomervilleite is a very rare phosphate mineral typically occurring as tiny, granular masses in phosphate-rich concretions. It is best known from the unique mineral localities of the Big Fish River area in Yukon, Canada, where it forms alongside other secondary phosphate minerals.

Hardness

4-5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrare

Johnsomervilleite

Hardness: 4-5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this johnsomervilleite?

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 johnsomervilleite with a known reference. Johnsomervilleite sits at Mohs 4-5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Johnsomervilleite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Johnsomervilleite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brown, pinkish-brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: granular.

Often confused with

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

Often found alongside johnsomervilleite

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

All properties

Chemical formula: Na₂CaMg₃Fe²⁺₂(PO₄)₄
Mohs hardness: 4-5
Density: 3.55 g/cm³
Colors: Yellow Brown Pinkish-brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Granular
Cleavage: None Observed
Rarity: Rare
Uses: Collector
Host rock: Phosphate-rich Sedimentary Concretions
Typical price: $50-250 for rare micro-mounts

Where rockhounds find johnsomervilleite

Classic worldwide localities

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

Field-hunting tip

Look in phosphate-rich sedimentary concretions country — that is the host setting where johnsomervilleite typically forms. If you start seeing gormanite, ludlamite, satterlyite in float, you are in the right ground. Field specimens usually show a granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify johnsomervilleite?+

Mohs hardness is 4-5. It typically shows a vitreous luster. The streak is white. Common colors include yellow, brown, pinkish-brown.

Where is johnsomervilleite found?+

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

How much is johnsomervilleite worth?+

Typical asking prices fall in the range of $50-250 for rare micro-mounts. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like johnsomervilleite?+

Johnsomervilleite is most often confused with Gormanite, Satterlyite, Ludlamite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with johnsomervilleite?+

Johnsomervilleite commonly co-occurs with Gormanite, Ludlamite, Satterlyite, Quartz, Siderite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does johnsomervilleite form in?+

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

What is johnsomervilleite used for?+

Johnsomervilleite is used in collector.

Find johnsomervilleite on the map

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