chemicool.com

v11gR TIL The Earth has enough Iron to make three new planets, each with the same mass as Mars
Zrk4 TIL the rarest element on Earth is the halogen Astatine. It’s so rare that only 30 grams of it can be found at any point in time on Earth, and only 0.05 micrograms of it has been produced to date. Most of its properties are unknown and no one has ever seen it in its natural form.
mOPy TIL that in 1669, Hennig Brand discovered phosphorus by boiling down urine and heating the residue to very high temperatures. He was trying to make gold though, and he hoped that the yellow color of urine meant there was gold in it.