This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
Serpentine derives its name from the mottled appearance of its surface, which is supposed to resemble the skin of a serpent. Pure serpentine is a hydrated silicate of magnesia, but it is generally found intermixed with lime carbonate, steatite or soapstone (a magnesia silicate), or with diallage, a foliated green variety of hornblende and dolomite. The prevailing colour is generally a rich green or red, permeated by veins of the white steatite. Some varieties have a base of olive green, with bands or blotches of rich brownish red, or bright red, mixed with lighter tints, or olive green, with steatite veins of greenish blue; some are red, studded with crystals of green diallage; some clouded, and some striped. Serpentine is massive or compact in texture, not brittle, easily worked, and capable of receiving a fine polish. It is so soft that it may be cut with a knife. It is generally obtained in blocks 2 to 3 ft. long, and it has been found that the size and. solidity of the blocks increase with their depth from the surface. This stone is greatly used in superior buildings for decorative purposes. It is, however, adapted only for indoor work, as it does not weather well, especially in smoky atmospheres.
The red varieties weather better than those of a greenish hue, and those especially which contain white streaks are not fit for external work.