Marcasite is very common mineral, but it is often ignored by mineral collectors. Despite its nice crystal forms, it lacks the luster of some other sulfides and its quite brittle. Its infamous instability in just slightly wet air does not help its popularity either.
Native sulphur is one of the few non-metallic and naturally occurring native elements. Despite huge drop of its industrial use, the native sulphur is still mined today. It can form highly aesthetic bright yellow crystals, which are very popular among mineral collectors.
Staurolite belongs to the scientifically important but otherwise quite overlooked minerals. It is not very popular among mineral collectors, as most of the specimens looks similar to each other. Also industrial application of staurolite is very limited.