slate
Black Slate
Black Slate is a fine-grained, foliated metamorphic rock, primarily formed from the low-grade regional metamorphism of mudstone or shale. Its composition mainly includes quartz, sericite, and chlorite, with darker hues often attributed to iron sulfide. The rock exhibits slaty cleavage, allowing it to split into thin, durable sheets.
- Quarry
- Buckingham County, Virginia, USA; Eastern Pennsylvania, USA; Jakhrana, Alwar District, Rajasthan, India
- Mohs hardness
- 2.5–5.5
- Water absorption
- < 0.25%
- ASTM spec
- ASTM C629
- Installed price
- $10–$50/sq ft installed
- Slab price
- $4–$12/sq ft slab
- Finishes
- Natural cleft, Honed, Sand rubbed, Gauged, Tumbled, Cascade, Textured, Brushed
- Applications
- Roofing, Interior Flooring, Exterior Paving, Wall Cladding, Stair Treads, Fireplace Surrounds, Countertops
- USA distributors
- Vermont Structural Slate Company; SiteOne Landscape Supply; North Country Slate; TileBar.com; Tilemart; Elit Tile; Portland Direct Tile & Marble; Surface Group
- Maintenance
- Slate generally requires minimal maintenance due to its low porosity and durability. Sealing is often recommended for interior applications, especially in wet areas or for lighter colored slates, to prevent staining.