Osmium, a group 8 d-block transition metal discovered in 1803 by the English chemist Smithson Tennant, is the rarest of the stable elements. Concentrations in the Earth’s crust are around 50 parts per trillion. The metal is found in nature uncombinrd or alloyed with its neighbour, iridium, in the alloys iridosmine or osmiridium. Around 500Kg

Lithium (Li, Element 3) Lithium, first member of the group 1 alkali metals, was discovered in 1817 by Johan August Arfwedson. It’s been around since the dawn of (astronomical) time- both stable isotopes, Li6 and Li7, being among a small handful of elements created in the Big Bang.1Terrestrially its highly abundant in seawater (up to