Qualities of Purple Slate
Purple slate, red and purple slate contain oxidized iron, this is the source of the unique rich colors.. This is generally a very hard stone, not easy to work or easy on the saws and machinery, but possessing the characteristics of beauty and longevity. Occasionally, as in the purple slates of north Wales and Vermont, reduction spheres form around the 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 the cleavage plane of the specimen, an over abundance will result in what is sometimes called mottled.
The classic Welsh slate, known as Penrhyn Purple, has dark plum coloring. It first arrived in the U.S. aboard sailing ships in the early 1800's many times as ballast and a product of the historic “triangle trade” it still graces many historical buildings around the country today. A beautiful, smooth and very durable stone whose popularity helped spur the exploitation and production of the Vermont-New York Slate Valley. Most times we find purple as an accent color in some of the “blends”, the most well known being the Vermont Blend, a general mixture of approximately 15- 30% purple with either a sea green or an unfading green, also often as a trim color or perhaps as part of a color pattern or floral/rosette decorations.
One of the earlier and well known USA purple quarries was the “Farnum Quarry” opened in 1853 in Poultney, VT, by William L. Farnum and son. This quarry produced a fine grained dark stone of excellent quality and still can be seen on many homes and barns in and around the Poultney area, over 150 years later. Many times purple is found lying in beds along with sea green, as in the old Davis and Roberts Quarry first opened in 1874, or the “Hooker Quarry” opened in 1872, also in the Poultney Township. The Eagle Quarry, the Lucky Strike, the Imperial, the Griffin, the Darius, Richie Brothers and the old Sheldon Quarry in Rupert, to name just a few, produced hundreds of thousands of squares of magnificent purple back in the day, as they say.
The amount of purple slate being presently quarried is but a fraction of that from the glory days, still a bit found here and there among the sea green and a few all purple small quarries in Poultney and the surrounding area still producing. Not a month goes by without one of our international customers asking “do you have any unfading purple?” Many have speculated, some have invested and others are actively exploring for the next great purple vein, through out the world there is a great demand for an unfading purple, can it be filled?