(See under Cornubite, Cornwallite, Clinoclase and Strashimirite.)
Cornwallite appears as tiny dark green crystals, while clinoclase forms greenish blue, radiating crystal groups.
Extensive collecting at the abandoned mines has revealed over 65 mineral species in a complex polymetallic quartz vein system, including bismutoferrite, bismutostibiconite, clinobisvanite, koechlinite, namibite, schumacherite, posnjakite, wroewolfeite, idaite, cornwallite
, clinoclase, cornubite and lindgrenite.
The Smale/Royal Society exhibit included the world's best liroconite and the world's best clinoclase "ball" of dark green crystals on matrix, as well as superb specimens of chalcocite, langite, olivenite, cornwallite
The pale green color may distinguish conichalcite from cornwallite (bright green), a commonly associated mineral in the Dolores and Umbria de Ramonete prospects.
Cornwallite appears as 1-mm spherules and as 2-mm to 3-mm clusters of spherules of a transparent, emerald-green color; at the La Atalaya prospect the spheres cover large surfaces, making this a significant locality for the mineral.
Cornwallite was reported without description by Guilbert and Zeihen (1964).
In places it is associated with cornwallite (Balestra, 1992; 1993).