I had to look it up, too...

Gossan (eiserner hut or eisenhut: German for "iron hat") is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.

"exposed part of an ore deposit or mineral vein" are such lovely words.

So those beautiful dark green rocks on the LBSR website photo gallery are "gossans". They are what JB and team were looking for, and found. JB called them "direct evidence" in the October NR I wrote about in an earlier post "direct evidence."