Limestone
Limestone is sedimentary (carbonate), (mostly CaCO₃). In the hand, it rates 3 to 4 (aggregate) on the Mohs scale, and it runs gray and tan. Soft gray-to-cream sedimentary stone that fizzes enthusiastically in vinegar and often carries visible shell fossils. Worldwide, former seafloors; from the white cliffs of Dover to the stone of the Great Pyramids.
The geology.
Limestone carries the formula (mostly CaCO₃). It belongs to the, system. Its listing category is sedimentary (carbonate).
It sits at 3 to 4 (aggregate) on the Mohs scale. The surface reads dull to earthy. Light behaviour is opaque. Specific gravity runs 2.3 to 2.7. The streak is white. It breaks with uneven fracture.
Soft gray-to-cream sedimentary stone that fizzes enthusiastically in vinegar and often carries visible shell fossils.
It turns up mostly as building stone, fossil slabs, septarian host or tumbled.
The origins.
Worldwide, former seafloors; from the white cliffs of Dover to the stone of the Great Pyramids.
On value, the database notes: common and very affordable.
Traditional associations.
In energy work traditions, associated with foundations and accumulation of experience.
This is lore, and we label it as lore. The measurable facts are further up the page.
Spotting the real thing.
Soft gray-to-cream sedimentary stone that fizzes enthusiastically in vinegar and often carries visible shell fossils.
| Looks like | How to tell them apart |
|---|---|
| Marble | Marble is recrystallized, sugary sparkle, no fossils; limestone is dull and often fossiliferous |
| Sandstone | Sandstone is gritty and never fizzes |
| Howlite | Howlite doesn't fizz in cold vinegar |
At-home tests.
A loupe and a window seat settle most questions about limestone. No workshop required.
| Test | What you should see |
|---|---|
| Acid check | Vigorous fizz with vinegar |
| Scratch check | Knife scratches easily |
| By eye | Look for shell and crinoid fragments |
Destructive tests belong to a gemologist, not a kitchen table. If a piece matters to you, pay for an appraisal before you take a file to it.
Care & handling.
At 3 to 4 (aggregate) on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with uneven fracture, which is worth knowing before you set it or drop it.
Clean it by hand, dry it properly, and keep it away from ultrasonic cleaners and hot steam.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is (mostly CaCO₃). Crystal system:,. Specific gravity: 2.3 to 2.7. Streak: White. Cleavage and fracture: Uneven fracture.
How it reaches the market
Worldwide, former seafloors; from the white cliffs of Dover to the stone of the Great Pyramids.
What it gets confused with
Marble: Marble is recrystallized, sugary sparkle, no fossils; limestone is dull and often fossiliferous. Sandstone: Sandstone is gritty and never fizzes. Howlite: Howlite doesn't fizz in cold vinegar.
What it is worth
Common and very affordable.
One more thing
Most limestone is biological, compacted shells, coral, and plankton; you can often see the sea creatures it's made of.
An education-first guide.
We do not stock limestone. Writing it up regardless is the point of a reference library.
Explore the Crystal Guide