Bettertonite is a rare aluminum arsenate, typically white. It was approved as a distinct mineral species in 2014. It was first described from the Penberthy Croft mine, St. Hilary, Cornwall, England.

Hardness

Mohs

Luster

Vitreous to Pearly to Silky

Streak

White

Transparency

Translucent

mineralrare

Bettertonite

Bettertonite is a rare aluminum arsenate, typically white. It was approved as a distinct mineral species in 2014. It was first described from the Penberthy Croft mine, St. Hilary, Cornwall, England.

Hardness: 2
Luster: Vitreous to Pearly to Silky
Streak: White
Transparency: Translucent

No image

Is this bettertonite?

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

Often confused with

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

mineral

Hydrotalcite

Mohs 2

How to tell apart: Luster reads vitreous to pearly to silky on Bettertonite and greasy to waxy on Hydrotalcite.

How to tell apart: Luster reads vitreous to pearly to silky on Bettertonite and pearly on Meixnerite.

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Often found alongside bettertonite

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

All properties

Chemical formula: Al₆(AsO₄)₃(OH)₉(H₂O)₅·11H₂O
Mohs hardness: 2
Density: 2.02 g/cm³
Colors: White Pale Orange
Streak: White
Luster: Vitreous to Pearly to Silky
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy Crystals
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Sedimentary Strata

Where rockhounds find bettertonite

Classic worldwide localities

Betterton, Maryland, USA

Field-hunting tip

Look in sedimentary strata country, the host setting where bettertonite typically forms. If you start seeing calcite, dolomite 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 bettertonite?+

Mohs hardness is 2. It typically shows a vitreous to pearly to silky luster. The streak is white. Common colors include white, pale orange.

Where is bettertonite found?+

Notable localities include Betterton, Maryland, USA.

Is bettertonite safe to handle?+

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

What rocks look like bettertonite?+

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

What minerals are found with bettertonite?+

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

What kind of rock does bettertonite form in?+

Bettertonite typically forms in sedimentary strata. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bettertonite used for?+

Bettertonite is used in collector.

Find bettertonite on the map

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