Fascinating rocks and minerals - set of 6 pieces

A very interesting set, which will be interesting and inspiring for both beginner "mineralogists" and more advanced ones. It contains six different fragments of rocks and minerals, each 3-4 cm in size: pyrite ("fools' gold"), scoria, obsidian, coarse granite, marble, Iceland spar (variety of calcite). Thus, it contains rocks (intrusive and extrusive rocks, metamorphic rocks) and minerals with interesting, and not obvious properties. You will find a piece of Iceland spar, which is characterized by double refraction; it is enough to put a spat crystal on a printed sheet of paper to see what this special feature is all about - you will see objects as doubled. Another piece is a pyrite called fool's gold because of its similarity to this precious ore; in fact, it is iron sulphide (II), and its name comes from the Greek word which means sparking, because when struck with flint it creates sparks.

Only 6 specimens, and how many interesting stories...