Grossular is a calcium-aluminum garnet that ranges in color from the vibrant green of Tsavorite to the cinnamon-brown of Hessonite. It is most commonly found in contact metamorphic rocks, specifically skarns, where limestone has been altered by igneous intrusions. Collectors should look for distinct dodecahedral crystal forms and its characteristic vitreous luster.

Hardness

6.5-7.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralcommonGarnet Group family

Grossular

Hardness: 6.5-7.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this grossular?

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 grossular with a known reference. Grossular sits at Mohs 6.5-7.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Grossular leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Grossular typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: green, brown, yellow, orange, red, colorless.
5
Look at form & habit
Crystal system: cubic. Typical habit: dodecahedral or trapezohedral crystals, massive, granular.

Often confused with

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

How to tell apart: Luster reads vitreous on Grossular and adamantine on Zircon.

Compare →

Often found alongside grossular

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

All properties

Chemical formula: Ca₃Al₂(SiO₄)₃
Mohs hardness: 6.5-7.5
Density: 3.5-3.6 g/cm³
Colors: Green Brown Yellow Orange Red Colorless
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Cubic
Crystal habit: Dodecahedral or Trapezohedral Crystals, Massive, Granular
Cleavage: None
Rarity: Common
Uses: Collector, Gemstone, Lapidary
Host rock: Metamorphosed Limestones and Skarns
Typical price: $10-50 per specimen, $50-500+ for high-quality faceted gems

Where rockhounds find grossular

Classic worldwide localities

Quebec, Canada
Tanzania
Mexico
Italy
Kenya
Russia

Field-hunting tip

Look in metamorphosed limestones and skarns country — that is the host setting where grossular typically forms. If you start seeing calcite, diopside, vesuvianite in float, you are in the right ground. Field specimens usually show a dodecahedral or trapezohedral crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify grossular?+

Mohs hardness is 6.5-7.5. It typically shows a vitreous luster. The streak is white. Common colors include green, brown, yellow, orange.

Where is grossular found?+

Notable localities include Quebec, Canada; Tanzania; Mexico; Italy; Kenya.

How much is grossular worth?+

Typical asking prices fall in the range of $10-50 per specimen, $50-500+ for high-quality faceted gems. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like grossular?+

Grossular is most often confused with Andradite, Vesuvianite, Zircon. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with grossular?+

Grossular commonly co-occurs with Calcite, Diopside, Vesuvianite, Epidote, Wollastonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does grossular form in?+

Grossular typically forms in metamorphosed limestones and skarns. Working float back to the host body is the standard way to chase a fresh occurrence.

What is grossular used for?+

Grossular is used in collector, gemstone, lapidary.

Find grossular on the map

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