Laurentianite is a rare pyroxene group mineral primarily found in highly alkaline igneous environments like the Mont Saint-Hilaire complex. Collectors typically identify it by its specific associations with rare-earth bearing minerals in intrusive pegmatites and miarolitic cavities.

Hardness

5-6

Mohs

Luster

Vitreous to satiny

Streak

White

Transparency

Translucent

mineralrare

Laurentianite

Hardness: 5-6
Luster: Vitreous to satiny
Streak: White
Transparency: Translucent

No image

Is this laurentianite?

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 laurentianite with a known reference. Laurentianite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to satiny.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals.

Often confused with

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

mineral

Aegirine

Mohs 6

How to tell apart: Streak differs, so Laurentianite leaves white, Aegirine leaves pale yellowish gray.

Often found alongside laurentianite

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

All properties

Chemical formula: [NbO(H₂O)]₃(Si₂O₇)₂[Na(H₂O)₂]₃
Mohs hardness: 5-6
Density: 2.464 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous to satiny
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Tabular crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: From a highly oxidized waste-rock pile of siderite-dominant pods attributed to altered sodalite syenite

Where rockhounds find laurentianite

Classic worldwide localities

Poudrette quarry, Mont Saint-Hilaire, Montérégie (formerly Rouville County), Quebec, Canada

Field-hunting tip

Where it forms: From a highly oxidized waste-rock pile of siderite-dominant pods attributed to altered sodalite syenite. If you start seeing quartz, pyrite, franconite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify laurentianite?+

Mohs hardness is 5-6. Luster: vitreous to satiny. The streak is white. Common colors include colorless.

Where is laurentianite found?+

Notable localities include Poudrette quarry, Mont Saint-Hilaire, Montérégie (formerly Rouville County), Quebec, Canada.

What rocks look like laurentianite?+

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

What minerals are found with laurentianite?+

Laurentianite commonly co-occurs with Quartz, Pyrite, Franconite, Rutile, Lepidochrocite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does laurentianite form in?+

Where it forms: From a highly oxidized waste-rock pile of siderite-dominant pods attributed to altered sodalite syenite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is laurentianite used for?+

Laurentianite is used in collector.

Find laurentianite on the map

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