Angastonite is a very rare hydrated calcium magnesium aluminum phosphate mineral. It typically occurs as small, delicate platy crystal aggregates within phosphate-rich zones in marble deposits.

Hardness

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrare

Angastonite

Angastonite is a very rare hydrated calcium magnesium aluminum phosphate mineral. It typically occurs as small, delicate platy crystal aggregates within phosphate-rich zones in marble deposits.

Hardness: 2
Luster: Pearly
Streak: White
Transparency: Translucent

Is this angastonite?

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 angastonite with a known reference. Angastonite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Angastonite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Angastonite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals.

Often confused with

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

mineral

Wavellite

Mohs 3.5-4

How to tell apart: Wavellite is the harder of the two (Mohs 3.5-4 vs. 2); luster reads pearly on Angastonite and vitreous on Wavellite.

How to tell apart: Variscite is the harder of the two (Mohs 3.5-4.5 vs. 2); luster reads pearly on Angastonite and waxy on Variscite.

Compare →

Often found alongside angastonite

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

All properties

Chemical formula: CaMgAl₂(PO₄)₂(OH)₄·7H₂O
Mohs hardness: 2
Density: 2.16 g/cm³
Colors: White Colorless
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Platy Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Phosphate-rich Deposits in Marble
Typical price: $50-300 per specimen

Where rockhounds find angastonite

Classic worldwide localities

Angaston, South Australia, Australia

Field-hunting tip

Look in phosphate-rich deposits in marble country — that is the host setting where angastonite typically forms. If you start seeing apatite, dolomite, quartz in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify angastonite?+

Mohs hardness is 2. It typically shows a pearly luster. The streak is white. Common colors include white, colorless.

Where is angastonite found?+

Notable localities include Angaston, South Australia, Australia.

How much is angastonite 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 angastonite?+

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

What minerals are found with angastonite?+

Angastonite commonly co-occurs with Apatite, Dolomite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does angastonite form in?+

Angastonite typically forms in phosphate-rich deposits in marble. Working float back to the host body is the standard way to chase a fresh occurrence.

What is angastonite used for?+

Angastonite is used in collector.

Find angastonite on the map

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