When subjected to significant geological forces, limestone deposits can undergo metamorphic transformation, resulting in their recrystallization into marble.
The categorization of limestones and marbles can be difficult for those without expertise in geology. It’s not uncommon for the same stone to be labeled as limestone in one situation and as marble in another, leading to confusion.

Limestone is primarily made of calcium carbonate (calcite) or a combination of calcium and magnesium carbonate (dolomite). It often contains small fossils, shell pieces, and other fossilized remains. Although these features are often visible to the naked eye upon close examination of the stone, their visibility can vary. Certain variations of limestone exhibit an exceptionally fine grain structure. Typically, limestone exhibits a uniform coloration ranging from pure white to off-white. Limestone commonly appears gray, although it can also exhibit white, yellow, or brown hues. This soft rock is prone to scratching and readily reacts with common acids, effervescing upon contact. Many variations of limestone lack the ability to achieve a high polish, leading to a matte, non-reflective surface.

Common Limestone Varieties:

• Calcarenite: Comprised of sand-sized calcite grains often containing small fossils, shell fragments, and debris. Some calcarenites may include oolites, leading to the classification of oolite limestone, a subtype of calcarenite.
• Coquina: Characterized by large, unaltered shell fragments loosely held together by calcite. It typically exhibits a coarse and porous texture, often comprising oyster and sea shells.
• Dolomite: A sedimentary carbonate rock composed of calcium and magnesium carbonate, also known as “magnesium limestone,” with a magnesium carbonate content ranging from 5% to 40%.
• Microcrystalline Limestone: Featuring crystals too small to be visible without magnification, this limestone variety presents a fine-grained structure.
• Oolitic Limestone: Composed of calcite-cemented calcareous stone and shell fragments, oolitic limestone lacks crystalline structure and is highly uniform in composition and texture, adapting well to temperature changes.
• Travertine: A calcium carbonate stone, usually light in color, formed from solids deposited in groundwater, often exhibiting high porosity or a cellular structure.

Just like marble and other calcareous stones, limestone is vulnerable to acids and can be dissolved by them. It’s advisable to avoid acidic products when cleaning or maintaining limestone and marble surfaces to preserve their integrity. The natural process of weathering can have detrimental effects on both the aesthetics and structural stability of limestone. Rain, snow, temperature changes, wind, and airborne pollutants all play a role in this deterioration.