S
TONECARE TECHNIQUESSLATE
Slate with its natural colors, varied
multicolored patterns and textures provide this stone
with a distinctive appearance.
GROUP |
Metamorphic | ||
COMMON ROCK-FORMING MINERAL GROUP |
Silicates | ||
COMPOSITION |
Muscovite, chlorite, kaolinite, micas, quartz and other accessory minerals (wide variation in composition) | ||
HARDNESS |
Soft to as Hard and dense as granite | MOHS' SCALE | 2.5 - 5.5 |
POROSITY % |
0.4 - 5 | ABSORPTION % | 0.1 - 1.7 |
WEATHERING |
Do 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. *See Notation |
||
TENDENCIES |
Absorbs oils and liquids...Softer/medium varieties scratches easily. | ||
COLORS |
Colors very widely. | ||
FINISHES |
Natural Cleft...Honed...Some types my be Flamed. | ||
NOTATIONS |
Sealing to minimize staining...Colored slates benefit from color enhancing treatments designed to magnify and protect the natural colors. When dealing with colored slates there are two distinct types, Fading and Unfading. After a period of exposure to the environment (sun/water) fading slates will alter generally to a lighter color. The unfading varieties will retain their true colors. Multi-colored slates used for flooring will undergo color changes in abrasive foot-traffic areas. The colors in these varieties of slates are in thin bedded layers...Some slates will dust for awhile after installation on floors as loose scale is removed by foot traffic. This will stop as the surface settles in, usually in a few weeks...*The majority of the multi-colored slates are what are termed "clay slates" and generally have a high content of clay minerals and are geologically classed as a low-ranked slates, those in which the metamorphic process was halted at a very early stage. These slates weather poorly in exterior wet/humid climates. | ||
Slate is a fine grained metamorphic stone
formed from clay mud; composed of sediments
of decomposed stone and organic matter that has been hardened by heat and pressure.
Since the geological process varies greatly, slates range quite a bit in hardness and
porosity.
Commercially "Slate" has become a trade term. This has lead to the classifying of some
stone types as slate. An example of this is using "Shale" that's been
commercially classified
as "slate", (most slates where a shale before the metamorphic process). Shale
weathers
poorly and very poorly in wet/humid climates. Soon after installation in exterior
applications
this stone crumbles, spalls excessively and can literally turn to power.
It's important to judge the
performance characteristics of different slates individually and
not assume that all slates are alike.
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