No surprise there, since slate had been quarried in north Wales since Roman times. Techniques of quarrying the rock, splitting it and trimming to size were already well-established. Rapidly-growing cities in England demanded a non-flammable roofing material – a need answered in abundance by the giant quarries of north Wales. It was, however, a dangerous occupation, overseen by English owners, and when news came of slate to the New World, thousands were willing to risk the dangerous crossing to begin their work lives anew, hopefully in better circumstances.
The first recorded use of slate as a roofing material was in Delta, Pennsylvania, in 1734. Local quarries produced ‘Peach Bottom Slate’, named after a nearby township and many thousands of homes in the area still boast this fine product. In 1787, slate quarries were opened in Arvonia, Virginia, and by the mid-19th century commercial quarrying was underway in Vermont, New York, Georgia and Alabama.
The primary use was for roofing, but soon ‘architectural slate’ commanded a robust market. Slate found use as thresholds, sinks, window sills, treads and risers for stairways, blackboards, billiard tables and fire surrounds. These products became enormously popular, employed in institutional use or to elaborately detail the homes of the affluent. Marble was considered a more exotic material than slate and became its natural competitor, in response to which marbleising techniques were introduced from Europe. Elegant designs were painted and backed onto the slate.
Slate’s natural qualities – being impervious to water, its relative ease of honing and polishing and extreme strength – kept it in the forefront until cheaper materials emerged. Its main handicap was its great weight, preventing efficient transportation – and the prevalence of slate artifacts are invariably within close range of the quarry of origin. This is demonstrated well in New England, where the highly-prized ‘Monson Black Slate’ from Monson, Maine, was very popular – and still is. Owners of 100-year-old pieces make the trek to Monson, where John Tatko of the Sheldon Slate Co still fabricates and refurbishes slate artifacts. These are carefully taken apart, cleaned and reassembled. High-tech glues replace the original plaster of Paris, but the original patina, softened with age, remains in place – its signature beauty.
The Slate Valley straddles the New York/Vermont line, just south of Lake Champlain. While only 20 miles long and 10 wide, it contains the largest concentration of slate quarries in the US and the most colourful slate in the world. A deep, earthy red is found on the New York side, grading, sometimes in the same quarry, to purple and mottled purple, full of green inclusions. A wide range of green – unrepeatable as natural phenomenon – with black and grey slate complete the colour spectrum. Slate is described as ‘unfading’ or ‘weathering’. Unfading is self-explanatory, while weathering slate can oxidise to display a further wide range of colours.
In Granville, New York, John’s brother, Pete Tatko, runs the other half of the Sheldon Slate Co, showing off the natural product is the drive behind Pete’s creations. Complex kitchen counters, sinks, floor tile and institutional products fill his shop, where an average of 75 people work. Quarrying architectural slate is different to that of roofing slate. It requires more ‘finesse’ – black powder, not dynamite! The quality must be perfect as the tiniest fracture would spell doom to a 12ft counter top. Impurities in slate that make it unsuitable for roofing material add to its desirability for other purposes: pyrite, a gold-coloured, crystal formation often found in slate, laces through the material in delicate patterns. The depth and subtle variation of colours are captivating.
Across the Slate Valley is Vermont Structural Slate, another family-run business. Craig Markcrow and Business Partner, Doug Sheldon, provide custom-cut stone projects, fabricated from Vermont and Virginia slate. They extend their material inventory to granite, marble, quartzite and sandstone, focusing their attention on design and architectural applications.
Slate is a material of endless possibilities. The sheer presence of rock slabs, stone that few people see in their daily lives, demands attention. Used aesthetically, artisanally or functionally, slate is a stone that draws in the observer. For all its centuries of use, it invariably prompts the question, ‘What is that?’ And it is this intrigue and mystery that creates its cache as an essential element in interior design.