Natural slate Samaca
02december
Natural slate Samaca - the history of shale quarries
Natural slate has been used for centuries as a reliable and durable roofing material. The waterproofness of a shale-covered roof is achieved thanks to the high qualifications of roofers, who have honed their skills for centuries and passed their knowledge from generation to generation; in some countries, this way whole generations and dynasties of roofing masters were formed.
Slate is a fire-resistant, non-porous and environmentally friendly stone with many natural features that make it one of the most valuable building materials on the construction market. In Europe, most slate roofs have a lifespan of more than 100 years, and in England there are slate roofs over 200 years old and they are still in excellent condition, only wood is thin and requires replacement. Often, slate after reconstruction is reused on other less significant projects.
Natural slate
Formed natural slate, like all other shale, is a metamorphic rock, which means that the first stone has undergone a chemical transformation to become a finished product. Possessing similar properties with sedimentary rocks, the shales were compressed and heated for thousands of years, the clay in the slate was destroyed and turned into the so-called mica.
Mica, from the Latin word “micare”, allows the newly formed stone to crack along the plane. This is one of the properties that allows you to manually split large shale billet by hand using only a hammer and chisel. Slate also contains quartz, the high level of which contributes to the brilliant appearance of the slate that shimmers in the sun.
The geological location and chemical composition determine the different color and density of the slate. Gray shale predominates in the European geological fault, and in England and America there are deposits of slate of different colors (purple, red, green, etc.), but their reserves are limited.
All shales contain iron pyrites, nicknamed “fools of gold” for their misleading appearance, they are iron sulfides that are either “stable” or “unstable” in terms of shale makeup.
Stable pyrites underwent tremendous temperature and high pressure and, thus, crystallized, forming small clusters in the stone similar to gold particles.
Unstable pyrites, were subjected to less heat and pressure, therefore, they did not fully crystallize, and remain vulnerable elements in the structure of the stone.
Unstable pyrites will necessarily have the effect of the so-called "bleeding", the formation of rust on the surface of the slate, creating a trace of an ugly rusty drip.