Chessexite is an extremely rare sulfate-bearing silicate mineral primarily known from the alkaline igneous complex at Mont Saint-Hilaire. It typically forms small, colorless to white tabular crystals in cavities of intrusive rocks, often requiring micro-mineral identification techniques for accurate confirmation.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Chessexite

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

No image

Is this chessexite?

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 chessexite with a known reference. Chessexite 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. Chessexite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Chessexite 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.

Often confused with

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

mineral

Phillipsite

Mohs 4-5

How to tell apart: Phillipsite is the harder of the two (Mohs 4-5 vs. 2).

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Often found alongside chessexite

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

All properties

Chemical formula: (Na,K)₄Ca₂Al₆(Si₆O₂₀)(SO₄)₄·4H₂O
Mohs hardness: 2
Density: 2.44 g/cm³
Colors: White Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Rocks
Typical price: $50-200 per specimen

Where rockhounds find chessexite

Classic worldwide localities

Mont Saint-Hilaire, Quebec, Canada

Field-hunting tip

Look in alkaline igneous rocks country — that is the host setting where chessexite typically forms. If you start seeing analcime, microcline, sodalite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify chessexite?+

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

Where is chessexite found?+

Notable localities include Mont Saint-Hilaire, Quebec, Canada.

How much is chessexite worth?+

Typical asking prices fall in the range of $50-200 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like chessexite?+

Chessexite is most often confused with Phillipsite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with chessexite?+

Chessexite commonly co-occurs with analcime, microcline, sodalite, aegirine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chessexite form in?+

Chessexite typically forms in alkaline igneous rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is chessexite used for?+

Chessexite is used in collector.

Find chessexite on the map

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