Aldridgeite is a rare secondary zinc copper sulfate mineral often found as small, delicate, pale blue crystalline crusts in oxidized mine workings. It is primarily known from the Broken Hill ore body and requires careful handling due to its solubility and fragile nature. It is typically sought after by advanced systematic mineral collectors who specialize in rare sulfates.

Hardness

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrare

Aldridgeite

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

Is this aldridgeite?

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 aldridgeite with a known reference. Aldridgeite 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. Aldridgeite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Aldridgeite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: pale blue.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals, crusts.

Often confused with

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

mineral

Goslarite

Mohs 2

How to tell apart: Luster reads pearly on Aldridgeite and vitreous on Goslarite.

How to tell apart: Luster reads pearly on Aldridgeite and vitreous on Melanterite.

Compare →

Often found alongside aldridgeite

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

All properties

Chemical formula: (Zn,Cu)SO₄·4H₂O
Mohs hardness: 2
Density: 2.8-3.0 g/cm³
Colors: Pale Blue
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals, Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Oxidized Ore Zones
Typical price: $50-300 per specimen

Where rockhounds find aldridgeite

Classic worldwide localities

Broken Hill, New South Wales, Australia

Field-hunting tip

Look in oxidized ore zones country — that is the host setting where aldridgeite typically forms. If you start seeing smithsonite, cerussite, galena in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify aldridgeite?+

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

Where is aldridgeite found?+

Notable localities include Broken Hill, New South Wales, Australia.

How much is aldridgeite 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 aldridgeite?+

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

What minerals are found with aldridgeite?+

Aldridgeite commonly co-occurs with Smithsonite, Cerussite, Galena. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does aldridgeite form in?+

Aldridgeite typically forms in oxidized ore zones. Working float back to the host body is the standard way to chase a fresh occurrence.

What is aldridgeite used for?+

Aldridgeite is used in collector.

Find aldridgeite on the map

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