Spurrite is a relatively uncommon calcium silicate carbonate mineral typically formed during the contact metamorphism of limestone. Collectors should look for its distinctive bright yellow fluorescence under short-wave ultraviolet light, which is its most reliable diagnostic feature in field settings.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineraluncommon

Spurrite

Hardness: 5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this spurrite?

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 spurrite with a known reference. Spurrite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Spurrite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Spurrite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, gray, pale blue.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: granular, massive, rarely in flattened crystals.

Often confused with

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

mineral

Calcite

Mohs 3

How to tell apart: Spurrite is noticeably harder (Mohs 5 vs. 3).

How to tell apart: Larnite is the harder of the two (Mohs 6 vs. 5).

How to tell apart: Merwinite is the harder of the two (Mohs 6 vs. 5).

Compare →

Often found alongside spurrite

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

All properties

Chemical formula: Ca₅(SiO₄)₂(CO₃)
Mohs hardness: 5
Density: 2.71 g/cm³
Colors: Colorless White Gray Pale Blue
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Granular, Massive, Rarely in Flattened Crystals
Cleavage: Distinct in One Direction
Fluorescence: Bright Yellow Under SW UV
Rarity: Uncommon
Uses: Collector, Scientific Research
Host rock: Contact Metamorphic Zones in Limestone
Typical price: $10-50 per specimen

Where rockhounds find spurrite

Classic worldwide localities

Chukotka, Russia
County Antrim, Northern Ireland
Riverside County, California, USA
Velardena, Mexico

Field-hunting tip

Look in contact metamorphic zones in limestone country — that is the host setting where spurrite typically forms. If you start seeing calcite, gehlenite, larnite in float, you are in the right ground. Field specimens usually show a granular, massive, rarely in flattened crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify spurrite?+

Mohs hardness is 5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, gray, pale blue.

Where is spurrite found?+

Notable localities include Chukotka, Russia; County Antrim, Northern Ireland; Riverside County, California, USA; Velardena, Mexico.

How much is spurrite worth?+

Typical asking prices fall in the range of $10-50 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like spurrite?+

Spurrite is most often confused with Calcite, Larnite, Merwinite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with spurrite?+

Spurrite commonly co-occurs with Calcite, Gehlenite, Larnite, Merwinite, Grossular. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does spurrite form in?+

Spurrite typically forms in contact metamorphic zones in limestone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is spurrite used for?+

Spurrite is used in collector, scientific research.

Find spurrite on the map

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