What does skeletal mean in mineralogy ?

Skeletal : definition

This term designates the texture of a crystal or a crystalline aggregate of which only the frame of the building seems to have been laid. Skeletal textures result from incomplete crystal growth or selective dissolution, with some faces more susceptible to corrosion than others.
Skeletal vanadinite from Mibladen, Morocco
Skeletal magnetite from Payún Matru Volcano, Argentina
Skeletal cuprite from Chessy, Rhône, France