Alwilkinsite-(Y) is an exceptionally rare secondary uranium mineral typically found as small, delicate, yellow acicular crystals or efflorescent crusts. It forms in the oxidized zones of uranium-bearing pegmatites, often occurring as a late-stage alteration product.

Hardness

Mohs

Luster

Vitreous

Streak

Pale Yellow-green

Transparency

Transparent

mineralrareAlwilkinsite Group family

Alwilkinsite-(Y)

Hardness: 2
Luster: Vitreous
Streak: Pale Yellow-green
Transparency: Transparent

No image

Is this alwilkinsite-(y)?

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 alwilkinsite-(y) with a known reference. Alwilkinsite-(Y) 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. Alwilkinsite-(Y) leaves a pale yellow-green streak.
3
Read the luster
Hold the specimen under a strong light. Alwilkinsite-(Y) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellowish green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular crystals, efflorescent crusts.

Often confused with

Alwilkinsite-(Y) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Johannite

Mohs 2

How to tell apart: Streak differs, so Alwilkinsite-(Y) leaves pale yellow-green, Johannite leaves pale green.

How to tell apart: Streak differs, so Alwilkinsite-(Y) leaves pale yellow-green, Zippeite leaves yellow.

Compare →

Often found alongside alwilkinsite-(y)

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

All properties

Chemical formula: Y(UO₂)₃(SO₄)₂(OH)₇·7H₂O
Mohs hardness: 2
Density: 3.37 g/cm³
Colors: Yellowish Green
Streak: Pale Yellow-green
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Acicular Crystals, Efflorescent Crusts
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatite

Where rockhounds find alwilkinsite-(y)

Classic worldwide localities

Harding Mine, New Mexico, USA

Field-hunting tip

Look in granite pegmatite country, the host setting where alwilkinsite-(y) typically forms. If you start seeing uraninite, vandendriesscheite, kasolite in float, you are in the right ground. Field specimens usually show a acicular crystals, efflorescent crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify alwilkinsite-(y)?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is pale yellow-green. Common colors include yellowish green.

Where is alwilkinsite-(y) found?+

Notable localities include Harding Mine, New Mexico, USA.

Is alwilkinsite-(y) safe to handle?+

This mineral is radioactive. It contains toxic constituents. Contains uranium and heavy metals; radioactive and potentially toxic if ingested or inhaled as dust. Handle with gloves and wash hands thoroughly after contact. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like alwilkinsite-(y)?+

Alwilkinsite-(Y) is most often confused with Johannite, Zippeite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with alwilkinsite-(y)?+

Alwilkinsite-(Y) commonly co-occurs with Uraninite, Vandendriesscheite, Kasolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does alwilkinsite-(y) form in?+

Alwilkinsite-(Y) typically forms in granite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is alwilkinsite-(y) used for?+

Alwilkinsite-(Y) is used in collector.

Find alwilkinsite-(y) on the map

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