How to Speak Stone
Natural stone is a beautiful product. As with anything created by nature, it is highly variable. With so many classifications and descriptions there is some industry jargon, we’d love to let make you smarter about stone terminology.
Finish Terminology
Ashlar- stone façade of generally square or rectangular units having sawed or dressed beds. There are three generally recognized distinctions:
- random ashlar: ashlar set with stones of varying length and height so that neither vertical nor horizontal joints are continuous.
- coursed ashlar: Ashlar set to form continuous horizontal joints.
- stacked ashlar: Ashlar set to form continuous vertical joints
Fieldstone– irregularly shaped stone as found in a field
Guillotined- stone cut with a wedge, results in edges of low precision with a ragged, chipped appearance
Natural Cleft- Stone that is split or cleaved parallel to its stratification, yielding a surface with minor imperfections.
Quarried or Quarry Run– stone that has not been selected for its color (full-range of variability)
Rock-faced– rustic finish for veneer stone created with a split or chiseled face, and dressed along the stone’s perimeter to produce convex projection. Standard with limestone.
Sawed edge on top, Rock-faced edge on bottom (Pennsylvania flagstone treads)
Thermal Finish– a high temperature finishing process used to create a consistent textured finish
Dimensional Terminology
| Thin | Building | |
| Squares and Rectangles | Ashlar | Ashlar |
| Irregularly Shaped | Mosaic | Rubble |
| Thickness | 1”-3” | 3”-6” |
Flag or Flagstone- thin (1″-3″) rectangular shapes of stone used as paving surfaces. The top, bottom, and sides have all been sawed
Tile– Stone <3/4″ thick
Treads– Larger stone > 4 feet long. Depending on their use they may also be called:
- Treads– flat stone used as the step on a stair
- Hearths- large stone placed in front of a fireplace or fire chamber
- Caps or Capstones- stone placed at the top of column, pilaster, or wall
Color Terminology
Dive Deeper: Choosing a Stone
Pennsylvania Flagstone Colors– is categorized into two color categories
- Select Blue– characterized predominantly by blues
- Full Color– has the full array of blue, brown, and gray hues naturally found in the stone
Select Blue Pennsylvania Flagstone
Full Color Pennsylvania Flagstone
Want to get even smarter: https://www.naturalstoneinstitute.org/default/assets/File/consumers/glossary.pdf
VP of Natural StoneMike Gregorio
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