gossan

[ gos-uh n, goz- ]

/ ˈgɒs ən, ˈgɒz- /

a rust-colored deposit of mineral matter at the outcrop of a vein or orebody containing iron-bearing materials.

Also called iron hat.

Origin of gossan

1770–80; orig. dial. (Cornwall) < Cornish, derivative of gōs blood; akin to Welsh gwaed

gospodin, gosport, goss, gossaert, gossamer, gossan, gosse, gossip, gossipmonger, gossipy, gossoon

The gossan does not often carry much value, though it may show traces of minerals which suggest what may be found below.

The Economic Aspect of Geology |C. K. Leith
What is left is either iron oxide, “gossan,” or the oxides of the other metals.

Getting Gold |J. C. F. Johnson
These iron-stained rocks are variously called the "gossan," the "iron capping," the "colorado," or the "eiserner Hut" (iron hat).

The Economic Aspect of Geology |C. K. Leith
What is left is either iron oxide, "gossan," or the oxides of the other metals.

Getting Gold |J. C. F. Johnson

The ore in the gossan is very generally more valuable than it will be below, and this is especially true of gold and silver ores.

The A B C of Mining |Charles A. Bramble