Mineraloids and their features
A mineraloid is a naturally occurring mineral-like substance that does not demonstrate crystallinity. Mineraloids are amorph.
Chemical Formula : FeO(OH)·nH2O
Shungite is a black mineraloid made of up to 99 percent carbon. Mohs scale of shungite is around 3.5 -4
Chemical Formula : SiO2·nH2O (hydrated silica)
Mohs Scale : 5.5 - 6