Vimsite is an extremely rare arsenic-bearing mineral discovered in the alkaline rocks of the Kola Peninsula. It typically forms thin, transparent tabular crystals that can be found perched on other hydrothermal minerals in pegmatite cavities.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Vimsite

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

Is this vimsite?

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 vimsite with a known reference. Vimsite 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. Vimsite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Vimsite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, subparallel aggregates.

Often confused with

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

mineral

Pharmacosiderite

Mohs 2.5

How to tell apart: Luster reads vitreous on Vimsite and adamantine on Pharmacosiderite.

Often found alongside vimsite

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

All properties

Chemical formula: Ca₃(AsO₃OH)₂(AsO₄)₂·11H₂O
Mohs hardness: 2
Density: 2.44 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Subparallel Aggregates
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Alkaline Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find vimsite

Classic worldwide localities

Khibiny Massif, Kola Peninsula, Russia

Field-hunting tip

Look in alkaline pegmatites country — that is the host setting where vimsite typically forms. If you start seeing aegirine, natrolite, pectolite in float, you are in the right ground. Field specimens usually show a tabular crystals, subparallel aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify vimsite?+

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

Where is vimsite found?+

Notable localities include Khibiny Massif, Kola Peninsula, Russia.

How much is vimsite 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.

Is vimsite safe to handle?+

It contains toxic constituents. Contains arsenic, a toxic element. Handle with care, wash hands after touching, and avoid creating or inhaling dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like vimsite?+

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

What minerals are found with vimsite?+

Vimsite commonly co-occurs with aegirine, natrolite, pectolite, fluorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does vimsite form in?+

Vimsite typically forms in alkaline pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is vimsite used for?+

Vimsite is used in collector.

Find vimsite on the map

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