"The Mystery of Lyle and Louise"

Codeable, 3D-printed robotic hand for interactive STEM learning.

Black, soft; most widely mined.

Slaty cleavage; contains hematite.

Dense and massive.

Hematite-cemented quartz; orthoquartzite.

Light gray, fine small clasts.

Pure, large, transparent-to-translucent cleavages, Mohs’ hardness of 4.

Chlorite-bearing.

Gray to buff, with numerous ooliths and fossil fragments.

Gray, fine-grained, massive contact rock.

Pale pink felsite, with small sanidine phenocrysts.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Brownish black, intermediate stage between peat and bituminous coal.

Unpolished metamorphic rock with silky lusture, red-brown colour, and clear parallel intergrown quartz crystals.

Lustrous, black 'hard coal'.

Spinel group; black, dull metallic luster; common iron oxide.