Geologically, marble was once limestone that achieved metamorphosis from intense pressures and high temperatures within the earth. This process altered its crystalline structure and introduced other minerals that produced the valuable colors and veining so coveted.
Commercially, any stone capable of taking a polish – with the exception of granite – is known as marble. This includes travertine, onyx, serpentine, and limestone.
The most common uses of marble include interior and exterior wall cladding, paving, fireplace and hearth, lavatory tops, counter tops, table tops, statuary, and novelty items. It also has many non-architectural uses such as paint whitening and agricultural lime.
Onyx marble is a translucent, layered calcitic stone in pastel shades. It is typically formed in caves as stalactites and stalagmites by the slow precipitation of cold, mineral-rich water.
Onyx is commonly used for interior wall coverings. It can also be used on the exterior in warm environments or for light duty residential flooring. Onyx table tops and other novelty items such as lamps and vases exhibit unusual beauty, and are very popular in many parts of the world.
Limestone is a sandy sedimentary rock formed closer to the earth's surface; it often captures fossilized plant and animal life, such as skeletons and shells of sea creatures that lived in vast, warm seas millions of years ago. When the mineral dolomite is present, it makes the limestone harder and capable of being polished in the same manner as metamorphic marble.
Limestone is widely used as a building stone because it is readily available and easy to work with. Similar to marble and granite, limestone is processed for a wide range of interior and exterior building applications, including floor tiles, wall tiles, vanities & other surfaces, fireplaces, columns, balustrades, water tables, steps, thresholds & windowsills. Limestone can be polished to a high gloss finish, but is more commonly known for its honed (matte), tumbled (antique or acid washed), and natural (split face or rough) finishes, typically in neutral tones.
The type of stone one falls in love with is a matter of personal taste; the choice though is almost never wrong.