Steedeite is a very rare silicate mineral discovered in the alkaline rocks of Mont Saint-Hilaire. It typically forms as delicate, white-to-colorless platy or radiating crystal aggregates nestled within vugs of larger intrusive formations.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Steedeite

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this steedeite?

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 steedeite with a known reference. Steedeite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Steedeite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Steedeite 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: triclinic. Typical habit: platy crystals, radiating clusters.

Often confused with

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

mineral

Pectolite

Mohs 4.5-5

How to tell apart: Pectolite is the harder of the two (Mohs 4.5-5 vs. 3.5); luster reads vitreous on Steedeite and vitreous to silky on Pectolite.

How to tell apart: Serandite is the harder of the two (Mohs 4.5-5 vs. 3.5).

Compare →

Often found alongside steedeite

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

All properties

Chemical formula: Na₄Mn₂Si₁₀O₂₄(OH)₂·4H₂O
Mohs hardness: 3.5
Density: 2.42 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Platy Crystals, Radiating Clusters
Cleavage: Perfect {001}
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Complexes
Typical price: $50-300 per specimen

Where rockhounds find steedeite

Classic worldwide localities

Mont Saint-Hilaire, Quebec, Canada

Field-hunting tip

Look in alkaline igneous complexes country, the host setting where steedeite typically forms. If you start seeing eudialyte, microcline, nepheline in float, you are in the right ground. Field specimens usually show a platy crystals, radiating clusters habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify steedeite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is steedeite found?+

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

How much is steedeite 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.

What rocks look like steedeite?+

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

What minerals are found with steedeite?+

Steedeite commonly co-occurs with Eudialyte, Microcline, Nepheline, Aegirine. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does steedeite form in?+

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

What is steedeite used for?+

Steedeite is used in collector.

Find steedeite on the map

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