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, 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.