One specimen found in December 2005 has one side of the perimorph entirely composed of pyrite crystals (combining the cube and pyritohedron forms); the remaining sides of the perimorph are formed by a thin quartz layer.
One specimen found at the Huanzala mine shows a hollow calcite perimorph about 1.
One very interesting specimen found in the Morococha district in January 2004 is a matrix entirely covered by a white crust of tiny quartz crystals, a perimorph after a crust of cuboctahedral crystals to about 1 cm.
It is a quartz perimorph after platy rectangular crystals, probably of barite.
Perimorphs of phillipsite-Ca after gi-smondine or clay mineral (saponite?
Pseudomorphs and perimorphs of clay minerals after gismondine were also reported from basa-nites of Groft Teichelberg, Bavaria, by Pollmann and Keck (1990).
Perimorphs and pseudomorphs of clay minerals after gis-mondine, phillipsite-Ca and natrolite have been often reported (cf.
Perimorphs after calcite consisting of thin, dull white shells of gibbsite, fluorite and rarely doyleite, have been observed.
Perimorphs after cryolite have been found in both the upper and lower sills.
Admixed with gibbsite, doyleite commonly forms thin, shell-like perimorphs after cryolite from which the original cryolite has been partially or completely leached out.
White, elongated, often partially hollow perimorphs consisting of tiny quartz crystals after natrolite crystals up to 1.
In places it covers or replaces carbonates to form perimorphs