L201 Tuff

Fine-grained, blue-green, sedimentary texture. 
Slaty cleavage. 
Some patches of lighter and finer-grained material.

Slaty cleavage due to the alignment of chlorite and muscovite. 
Cross-cut by the blobs of the fine-grained material. These are orange-brown in thin-section. Could be water-lain ash, ripped-up to form clasts. 
Very fine-grained, brown matrix, probably volcanic ash. 
Carbonate, quartz and opaque clasts slightly larger than the matrix.

Fine-grained volcanic ash deposited by an explosive volcanic eruption has undergone low grade metamorphism to produce a slaty cleavage.

tuff