Nevada Creek Hidden Collection

Mineral Matters #675

This particular specimen was labelled simply as stichtite on serpentine from Dundas, Tasmania. This is a little problematic. The association with aragonite, and the particular dark purple hue place this as a Nevada Creek specimen. Nevada Creek is a bit north of Dundas.

Interestingly, many specimens from this locality have been labelled barbertonite instead of stichtite. Barbertonite is now a discredited species and is actually a structural variant (polytype) of stichtite (stichtite-2H).

Polytypism, derived from the Greek words πολύ (poly) meaning many, and τύπος (typos) meaning type, refers to the existence of different crystal structures for the same chemical compound. These different structures arise from variations in the stacking sequence of structurally identical layers or modules. The key characteristic distinguishing polytypism from polymorphism (different structures with different chemical compositions) is the identical chemical composition across all polytypes of a given substance.

So there is purple stichtite (or stichtite-2H) with colourless aragonite and translucent green serpentine, possibly lizardite. There are some unidentified dendrites too. Click on the photo below to zoom in and check them out. More Hidden Collection!

Below: Stichtite, Aragonite, Serpentine, Nevada Creek, Tasmania. Width of view 6mm.