Cool silver-grey with mica glitter — the contemporary ledger stone.
Silver quartzite is the cool-toned sibling of the golden variety: the same extreme hardness and mica flash, but in greys that run from pale platinum to graphite within a single panel.
It has largely displaced slate in ledger-panel work because it does not delaminate. Slate sheds layers over a decade of freeze-thaw; quartzite does not, which makes it the safer specification for any wall that will be exposed.
Against a dark window frame or a black metal railing it is one of the most quietly expensive-looking materials available.
Each of these opens the library filtered to everything suitable for that use, so you can see what Silver Quartzite is competing against.
Post the project and contractors working in your county bid on it — with this stone already specified.