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 the carbonate of magnesia occurring in limestone rises to about 45 per cent, the stone is then called dolomite. It is usually whitish or yellowish in color, and is a crystalline granular aggregate. It is harder than the ordinary limestones, and also less soluble, being scarcely at all acted upon by dilute hydrochloric acid. There is no essential difference between limestone and dolomite with respect to color and texture.