Alfredopetrovite is an extremely rare sulfate mineral identified by its occurrence in the oxidized zones of selenium-rich deposits. It typically forms small, clear, tabular crystals and is known for its distinct crystal chemistry within the copiapite group.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareCopiapite Group family

Alfredopetrovite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this alfredopetrovite?

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 alfredopetrovite with a known reference. Alfredopetrovite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Alfredopetrovite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Alfredopetrovite 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: trigonal. Typical habit: tabular to blocky crystals.

Often confused with

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

mineral

Copiapite

Mohs 2.5-3

How to tell apart: Streak differs — Alfredopetrovite leaves white, Copiapite leaves yellow; luster reads vitreous on Alfredopetrovite and pearly on Copiapite.

Often found alongside alfredopetrovite

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

All properties

Chemical formula: Na₃Al(SeO₄)₂(OH)₂·H₂O
Mohs hardness: 2-3
Density: 2.16 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Tabular to Blocky Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Zones of Seleniferous Ore Deposits
Typical price: $100-500 thumbnail size specimens

Where rockhounds find alfredopetrovite

Classic worldwide localities

Humberstone Mine, Chile
Santa Maria Mine, Chile

Field-hunting tip

Look in oxidized zones of seleniferous ore deposits country — that is the host setting where alfredopetrovite typically forms. If you start seeing euchlorine, glockerite, metavoltine in float, you are in the right ground. Field specimens usually show a tabular to blocky crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify alfredopetrovite?+

Mohs hardness is 2-3. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is alfredopetrovite found?+

Notable localities include Humberstone Mine, Chile; Santa Maria Mine, Chile.

How much is alfredopetrovite worth?+

Typical asking prices fall in the range of $100-500 thumbnail size specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is alfredopetrovite safe to handle?+

It contains toxic constituents. Contains selenium, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like alfredopetrovite?+

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

What minerals are found with alfredopetrovite?+

Alfredopetrovite commonly co-occurs with Euchlorine, Glockerite, Metavoltine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does alfredopetrovite form in?+

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

What is alfredopetrovite used for?+

Alfredopetrovite is used in collector.

Find alfredopetrovite on the map

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