Argillite (with Barnacles)

Hardness: 3-4 (Mohs scale), Color: Dark greyish-green to brownish, Luster: Dull/Earthy, Crystal Structure: Microcrystalline, featuring distinct sedimentary bedding planes accentuated by erosion.

Formed through the low-grade metamorphism of clay-rich sedimentary rocks (mudstone or shale). It lacks the fissility of shale and the foliation of slate. This specific piece shows marine barnacle encrustations, suggesting it was recently submerged in a coastal environment.

Historically used by indigenous peoples (like the Haida) for intricate carvings. In modern times, it is used for decorative carvings, sculptures, and occasionally as garden stone.

The distinct horizontal grooves are likely original sedimentary bedding planes that have been weathered out by ocean currents or wind. The small white specks are the remains of barnacle shells (balanomorphs).

Identify in the field by its fine-grained texture, lack of splitting into thin sheets (unlike shale), and its presence in coastal or tectonic uplift zones. Commonly found in the Pacific Northwest and British Columbia.