Cinnabar is bright red mercury sulfide, which is a main ore of mercury and used to be a source of red pigments for milleniums. Cinnabar (and mercury) had been a key to mining precious metals until beginning of the 20th century and also saved a millions of teeth.
Elemental bismuth occurs as a metallic silver mineral often characterized by an oxide tarnish generating a dramatic iridescence of pinks, yellows and greens.
Elemental mercury occurs in the rare natural form as a silver liquid globules. Mercury has extreme physical properties combined with very high toxicity, which makes it a very unusual collectors specimen.
Magnesite is not the most popular mineral for collectors but it can form outstanding specimens and crystals. However, its principal use is as a magnesium ore and a special refractory - a material where resistance to extreme temperatures is fundamental to an industrial process.
