Archerite is a rare phosphate mineral formed in cave environments where guano reacts with silicate minerals. It is typically found as fragile, colorless crystalline crusts and is highly soluble in water, requiring careful storage in a dry environment.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Archerite

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this archerite?

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 archerite with a known reference. Archerite 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. Archerite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Archerite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: small crystalline crusts and aggregates.

Often confused with

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

Often found alongside archerite

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

All properties

Chemical formula: (K,NH₄)H₂PO₄
Mohs hardness: 2
Density: 2.26 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Small Crystalline Crusts and Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Guano-rich Cave Environments
Typical price: $50-200 for small study specimens

Where rockhounds find archerite

Classic worldwide localities

Skipton Caves, Victoria, Australia

Field-hunting tip

Look in guano-rich cave environments country — that is the host setting where archerite typically forms. If you start seeing biphosphammite, struvite, taranakite in float, you are in the right ground. Field specimens usually show a small crystalline crusts and aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify archerite?+

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

Where is archerite found?+

Notable localities include Skipton Caves, Victoria, Australia.

How much is archerite worth?+

Typical asking prices fall in the range of $50-200 for small study specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like archerite?+

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

What minerals are found with archerite?+

Archerite commonly co-occurs with Biphosphammite, Struvite, Taranakite, Monetite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does archerite form in?+

Archerite typically forms in guano-rich cave environments. Working float back to the host body is the standard way to chase a fresh occurrence.

What is archerite used for?+

Archerite is used in collector.

Find archerite on the map

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