Slate is a fine-grained metamorphic rock of argillaceous origin formed by the composition of mud and stone sediment that splits into thin, smooth-surfaced layers. Slate Stones are chemically a multi-mineral rock made of a composition of minerals and colloidal substances. The mineral composition essentially consists of members of Mica group commonly sericite & muscovite,and and accessory minerals such as oxides, calcites, minor amounts quarts and feldspar along with some contents of ferro-magnesium minerals. The content of silica is normally poor. The Clay group commonly consists of paragonite, chlorite & kaonilite. This fine grained meamorphic rock formed of above composition of minerals and other organic substances has been hardened by heat and pressure. Since the geolgical process varies greatly from place to place, Natural Slate Stones hardness and porosity varies quite a bit.
Slate stones characteristics vary with source. It may be black, green, yellow, brown, red or mottled and is relatively dense. Many natural slate stones that are available today have wide ranging physical characteristics and overall suitability.
The natural slate stone differs in its density, tensile strength, absorbency and abrasion resistance.
|Composition||-||Muscovite,Cericite, chlorite,hematite, kaolinite, micas, quartz,clay and other accessory minerals (wide variation in composition).|
|Hardness||-||Soft - easily scratched. They can also be as hard and dense as granite|
|Absorption||-||Low - medium oil, water other liquids|
|Weathering characteristics||-||Due to the wide ranges of slate, this stone has wide ranges of weathering. Cleft planes provides permeability for water penetration resulting in spalling and flaking. Slates that have a high kaolinite content (a clay) display accelerated rate of deterioration in wet environments|
|Tendencies||-||Absorbs oils and liquids...Softer/medium varieties scratches easily.|
|Colors||-||Colors vary widely|
|Finish||-||Different finishes such as acrylic, wax, natural cleft, honed etc.|