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Materials - Serpentinite

Serpentinite is a rock composed of one or more serpentine minerlas. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultamafic rock from the Earth's mantle, usually in a submarine environment.

Serpentines describes a group of common rock-forming hydrous magnesium iron phyllosilicate minerals; they may contain minor amounts of other elements including chromium, manganese, cobalt and nickel. In mineralogy and gemology, serpentine may refer to any of twenty varieties belonging to the serpentine group. Owing to admixture, these varieties are not always easy to individualize, and distinctions are not usually made. There are three important mineral polymorphs of serpentine: Antigorite, Chrysotile and Lizardite.

Most green or 'verde' marbles are serpentinites and are considered seperately to true marble because its origin is often the result of the metamorphism of rocks other than limestones. The green colour is typically derived from the presence of serpentine minerals. These minerals are relatively soft and the structure often weak, the stone commonly requiring reinforcement from fibre glass matting glued to the underside.

Serpentinites are rarely used for whole floors and are preferred for providing coloured inserts or contrasting bands to the main field paving. Care must be taken to ensure their compatability with other stones.

A special consideration for any serpentinite is the presence or otherwise of asbestiform minerals that may be naturally present e.g. chrysotile (white asbestos) and the amphiboles tremolite and actinolite. It may be prudent to establish that, where present, fibres of these minerlas in the respirable range are not generated during any cutting, grinding and polishing operations, particularly if carried out dry.

The Asbetos (Prohibitions) Regulations have banned the impot; supply and use of blue, brown and white asbestos (crocidolite, amosite and chrysotile repectively) essentially when part of an asbestos admixture product. Natural stone that contains chrysotile for example, would not be classed as an asbestos admixture product.

We include here a palette of some of our most popular materials. This display is not extensive as there are many others to choose from that are available to us from worldwide resources.