Sinkankasite is a rare phosphate mineral occurring as delicate, thin bladed crystals or radial clusters. It is primarily found within complex granite pegmatites and is highly prized by mineral collectors due to its extreme scarcity and limited number of known localities.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Sinkankasite

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

Is this sinkankasite?

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 sinkankasite with a known reference. Sinkankasite 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. Sinkankasite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Sinkankasite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, pale yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: bladed crystals, radial aggregates.

Often confused with

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

Often found alongside sinkankasite

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

All properties

Chemical formula: H₂MnAl(PO₄)₂(OH)·6H₂O
Mohs hardness: 3.5
Density: 2.42 g/cm³
Colors: Colorless White Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Bladed Crystals, Radial Aggregates
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find sinkankasite

Classic worldwide localities

Foote Lithium Company Mine, North Carolina, USA

Field-hunting tip

Look in granite pegmatites country — that is the host setting where sinkankasite typically forms. If you start seeing gormanite, tinsleyite, quartz in float, you are in the right ground. Field specimens usually show a bladed crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify sinkankasite?+

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

Where is sinkankasite found?+

Notable localities include Foote Lithium Company Mine, North Carolina, USA.

How much is sinkankasite worth?+

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

What rocks look like sinkankasite?+

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

What minerals are found with sinkankasite?+

Sinkankasite commonly co-occurs with Gormanite, Tinsleyite, Quartz, Albite, Muscovite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does sinkankasite form in?+

Sinkankasite typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is sinkankasite used for?+

Sinkankasite is used in collector.

Find sinkankasite on the map

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