Where slate comes from

Have you ever wondered were slate comes from? Now the slate I am referring to is the type that is used on roofs. There are many different kinds of Slate roofing as you find out from this post. Slate roofing is normally named by the origin of where it came from. In the united states they are still being quarried in  Virginia, Pennsylvania, New York, and Vermont. 

But, Did you know that a century ago there were hundreds more American slate quarries than there are today, including in Maine and Georgia. And each one produced a different color and texture. Most your professional slate roofing contractors can tell you where it came from just by looking at it.

 Slate is made a lot differently theses days with new modern technology. But I remember reading that at a long time ago when limestone was used. They would pull the limestone out of the ground and some times have to go up to 70 feet deep to get it. It would be in a block that was refereed to as a pendle, and let it sit in a field and absorb water. And they would pile dirt on top of it and pore water on top of it to help with this proses. 

They would do this over the course of a few years!. I know right, that's a long time to wait. Over the course of a few cold winters the water that had absorbed would penetrate and split the stone in to usable pieces. 

The Picture above is a gazebo that is using the limestone roofing that I just spoke of. Buckingham slates (below), or Virginia slates, are a gray-black slate with a life expectancy of about 150 years, maybe more. You will see the glint of countless tiny silica crystals in this slate when viewed in the sun, a unique characteristic of Buckingham slate.

Slate is mainly composed of the minerals quartz and muscovite or illite, often along with biotite, chlorite, hematite, and pyrite and, less frequently apatite, graphite, kaolinite, magnetite, tourmaline, or zircon as well as feldspar. Occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids, which appear as ellipses when viewed on a cleavage plane of the specimen.

Always remember when having your slate or tile roof looked at or worked on you need to have a real slate and tile roofing contractor to do the work other wise it will cost you more money to get it done right. Below is a picture of a slte roof repaired by a asphalt shingle roofer who didn't have the right tools or the knowledge to do the repair.