Marble

1) In Geology, a metamorphic rock made up largely of calcite or dolomite.
2) In dimension stone, a rock that will polish and that is composed mainly of calcite or dolomite or, rarely, serpentine.

Marble, the most commonly referred to natural stone, is typically polished but also available in honed finishes. Ranges from fairly ‘soft’ to ‘somewhat hard’ as natural stones go. Massive array of colors and visual textures. Suitable for light commercial or normal residential use; typically unsuitable for very high-use or very high-traffic areas (many exceptions). Not suitable for Kitchen counter installations. The term is sometimes used (incorrectly from a technical standpoint) to include all natural stones.

Granite

1) In technical Geologic terms, igneous rock with crystals or grains of visible size and consisting mainly of quartz and the soldium or potassium feldspars.
2) In dimension stone, crystalline silicate rock with visible grains. The commercial term, therefore, includes other igneous rocks that are not granite in the strict sense

Granites are the densest of the natural stones, typically polished but also available in honed or flamed finishes. “Hard” to “very hard” as natural stones go, and therefore suitable for use in both commercial and residential in very high-use areas (very few exceptions). The “standard” natural stone for use in residential Kitchen counter applications.

Limestone

Rock of sedimentary origin composed principally of calcite or dolomite or both.

Limestone is a typically ‘soft’ natural stone, most often honed but depending on density can be polished. ‘Very soft’ to ‘medium’ as natural stones go (few exceptions), and generally quite porous. Suitable for light commercial and residential use. It’s use in medium to high-use areas is discouraged, but can be achieved with proper monitoring and maintenance. Not suitable for Kitchen counter installations.

Travertine

A variety of limestone deposited by hot or cold water as cavern fillings, including stalactites and stalagmites, or as accumulations at springs.

Travertine, usually included in the general grouping of Marble, is characterized by naturally occuring pits and fossils in the stone material, filled during the manufacturing process in the case of polished travertine. This characteristic fill typically yields a ‘semi-polished’ material. ‘Medium’ hardness as natural stones go, it is suitable for medium commercial and residential use. Some travertines are also available in unfilled form, lending a profound visual texture to the material (practicality notwithstanding). Not suitable for Kitchen counter installations.

Onyx

A banded, varicolored form of quartz.

Characterized by its translucency, Onyx is almost strictly a decorative stone. It’s typically high cost and fragility make it unsuitable for most usages. Beautiful, but should be considered ‘soft’ as natural stones go. Limited to vanities or low use areas residentially.