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, 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.