FIG. 2.

Gossan (G) rock textures. Characterized rock textures are divided into three groups: pyrite-dominated (PQB), quartz boxwork and HFO rocks (QBG), and iron-only (IO) rocks. PQB rocks include (a) pyrite (P) in altered rhyolite (Rh), (b) pyrite and jarosite group minerals (J) on altered rhyolite, and (c) pyrite with sulfate salts (including copiapite and halotrichite group minerals). QBG rocks include (d) HFO (G) with pyrite, (e) dull luster QBG, (f) brightly colored QBG, (g) broken-face interior of QBG, and (h) resinous luster QBG. IO rocks include (i) dendritic HFO masses (this IO rock is shown overlapping the dull luster QBG rock), (j) brightly colored laminated HFO, (k) dull laminated HFO, (l) coalesced vertical columns of HFO, (m) siliceous HFO mass, and (n) clast- and HFO-filament-bearing HFO masses. (Color graphics available at www.liebertonline.com/ast)