Limestone

Limestone is a fairly common sedimentary rock, typically composed of Calcite and Aragonite – forms of Calcium carbonate.

It is extremely important in industry for various things but primarily used for the production of Lime, important for things like cements, waste-water treatments, and chemical animal feeds.

Most of the pieces we sell are fossiliferous; most Limestone is made up of tiny fossil remains from corals – but larger fossils do occur too, often shells and crinoids.

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Appearance, Uses and History

Limestone is primarily used in industry, with huge amounts of it used in construction, agriculture, and as a raw material in a range of industries.

Many buildings are made partially or entirely out of limestone, and is used to make lime based mortars and cements. Many famous buildings in London are made from Portland Limestone – which gave its name to Portland cement – now one of the worlds most widely used substances.

In addition, many castles and churches around the UK and Europe are made of Limestone.

Limestone is heavily used in the production of Lime, which is known for treating soil, waste water purification, smelting, the production of quicklimes, cements, and mortars. It is also used as food supplements, and to remove impurities during metal smelts.

Limestone is affected by acidic solutions, which includes acid rain – which has caused serious damage to some structures, statues, etc made from the material.

Geologically this can cause an interesting landscape known as karst. A karst landscape is formed from limestone, which slowly dissolves in rainwater. This creates an almost alien fractured, sharp landscape.

 

Locales

I’m not listing locales – honestly, lets just say the entire planet. 🙂
There are a few highly fossiliferous exposures or sites that are important due to the fossils preserved within, however – the Much Wenlock, Wrens Nest and Great Orme in the UK stand out, as does the Solnhofen Limestone exposure in Germany.

Mineralogy

Chemistry
Composed mostly of CaCO3 (more than 50%), often a mixture of Calcite and Aragonite.
Colours and Variations
Variations include chalk, coquina, fossiliferous limestones, oolitic limestone, travertine, and tufa. The most common stalactites are actually made of Limestone, which precipitates from mineralised water in caves.
Streak
White
Luster
Mostly dull.
Fracture
Depends on how it formed – clastic limestones will fracture very differently to non clastic.
Transparency
Opaque, rarely translucent.
Crystal habit
Depends on how it formed – Limestone can be precipitated from mineral rich waters (non-clastic), secreted by marine organisms (biochemical limestone), form from the shells of deceased marine organisms and sea creatures (bioclastic limestone), and it can also form from the cementation of sands or muds (clastic limestone).
Mohs hardness
3-4
Specific Gravity
2.3-2.7, varies by composition.
Fluorescence
Sometimes, varies by piece and depends on composition.
Easiest testing method
Readily dissolves in acid, including vinegar; a drop of vinegar may be used to differentiate it.
Common Treatments
None.

Hazards and Warnings

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.

When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

Translations

Arabic:

  • حجر الكلس

Hindi:

  • चूना पत्थर

Portuguese:

  • calcário

Bengali:

  • চুনাপাথর

Indonesian:

  • batu kapur

Punjabi:

  • ਚੂਨਾ ਪੱਥਰ

English:

  • limestone

Italian:

  • calcare

Russian:

  • известняк

French:

  • calcaire

Japanese:

  • 石灰岩

Spanish:

  • caliza

German:

  • Kalkstein

Korean:

  • 석회암

Thai:

Gujurati:

  • ચૂનાનો પથ્થર

Mandarin and Traditional Chinese:

  • 石灰石

Urdu:

  • چونا پتھر

Further Reading / External Links

  • https://www.mindat.org/min-49160.html
  • https://en.wikipedia.org/wiki/Limestone
  • https://geology.com/rocks/limestone.shtml