Lime, specifically quicklime or calcium oxide, is an industrially processed product derived primarily from heating limestone. It is rarely found as a naturally occurring mineral due to its high reactivity with water and carbon dioxide in the atmosphere. Collectors primarily interact with it in historical industrial contexts or as processed chemical samples.

Hardness

3-4

Mohs

Luster

Dull

Streak

White

Transparency

Opaque

sedimentarycommon

Lime

Hardness: 3-4
Luster: Dull
Streak: White
Transparency: Opaque

Is this lime?

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 lime with a known reference. Lime sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Lime leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Lime typically shows a dull luster.
4
Match the color range
Compare against the expected color range: white, gray, yellow, tan.
5
Look at form & habit
Typical habit: massive.

Often confused with

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

sedimentary

Limestone

Mohs 3

How to tell apart: Luster reads dull on Lime and dull to earthy on Limestone.

How to tell apart: Lime is noticeably harder (Mohs 3-4 vs. 1).

Compare →

Often found alongside lime

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

All properties

Mohs hardness: 3-4
Density: 2.3-2.7 g/cm³
Colors: White Gray Yellow Tan
Streak: White
Luster: Dull
Transparency: Opaque
Crystal habit: Massive
Cleavage: None
Rarity: Common
Uses: Industrial, Construction, Agricultural
Host rock: Sedimentary Environments
Typical price: low

Where rockhounds find lime

Classic worldwide localities

United States
China
Germany
Italy
Mexico

Field-hunting tip

Look in sedimentary environments country — that is the host setting where lime typically forms. If you start seeing calcite, dolomite, clay minerals in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify lime?+

Mohs hardness is 3-4. It typically shows a dull luster. The streak is white. Common colors include white, gray, yellow, tan.

Where is lime found?+

Notable localities include United States; China; Germany; Italy; Mexico.

How much is lime worth?+

Typical asking prices fall in the range of low. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like lime?+

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

What minerals are found with lime?+

Lime commonly co-occurs with Calcite, Dolomite, Clay minerals. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does lime form in?+

Lime typically forms in sedimentary environments. Working float back to the host body is the standard way to chase a fresh occurrence.

What is lime used for?+

Lime is used in industrial, construction, agricultural.

Find lime on the map

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