This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
When limestone is wholly crystalline and suitable for ornamental purposes, it is called marble; or, in other words, any limestone that can be polished is called marble. There are a great many varieties of marble, and they vary greatly in color and appearance. Owing to the cost of polishing marble, it is used chiefly for ornamental purposes.