Magnesian Limestone. Magnesium carbonate is usually found in combination with calcium carbonate, and when about 47 per cent of the total carbonates is magnesium carbonate, the limestone is known as dolomite.
Ground Limestone is the stone pulverized so that it can be distributed. It is carbonate of lime (CaCO3), or a combination of calcium and magnesium carbonate, and in a way has a right to be designated as "lime," but such use leads to confusion.
Fresh Burned Lime. Calcium oxide (CaO) formerly was accurately designated as "lime," but the words "fresh burned" are often prefixed to prevent confusion with lime carbonate or the hydrate. It is known as "lump lime," "caustic lime" and "stone lime."
Ground or Pulverized Lime. Fresh burned lime may be ground fine, so that it can be spread on land without slaking. This product should not be confused with ground limestone or hydrated lime. Fresh ground lime is worth nearly twice as much per ton as ground limestone, but some of the product on the market is far from pure. There is opportunity to grind up unburned and waste material with the caustic lime, and this form of lime usually contains some hydrated material.
Hydrated Lime is the compound formed by the action of water or steam on fresh burned lime.
Air-Slaked Lime is a compound formed by the action of carbon dioxide from the air on hydrated lime, and its formula is CaCO3, which is that of pure limestone.
An Indiana Limestone Quarry