Quartz, gypsum and pirite

Obsidiana and unknow

The black one is a piece of obsidiana (kind of vulcanic glass) collected at Lake Naivasha area, Kenya; the other (unknown) was found at a beach in southern Portugal.

Ibis and Desert Rose

The ibis is made of soapstone.
Desert rose is the name given to rosette formations of gypsum (gesso) and barite, with sand inclusions.
Both brought from the Atlas chain, in Marocco.

Agate

Agate is the most common variety of chalcedony which is a form of quartz. It is, in fact, identical in composition and physical properties.