The crescent moon in the symbol represents the soul rising above the elements or the darkness of matter, symbolized by the cross below.
It is silvery -white and called "white lead" (Plumbum album) by the Romans who used it to make mirrors. It is soft but has a crystalline structure which results in it making a "cry" when a bar of tin is bent, breaking these crystals. Tin is a bactericide and pesticide and plates and cups made of tin were used in the Middle Ages to help sick people get well.
From Sorcerer's Stone by Dennis William Hauck: "The distribution of tin on earth follows an ecliptic at an angle of 23.5 degrees to the equator that is an exact track of the orbit of Jupiter slicing through the planet. Even stranger, these jovian forces seem to form tin veins that zigzag through the rocks in a lightning bolt pattern."
Flavius Josephus records that Jesus' uncle, Joseph of Arimethea, was a wealthy tin trader who traveled with Jesus to the British Isles, which at the time were known for their rich natural resources. This would make Joseph a "Tin Man" by trade.
Correspondences of Tin
Sign: Saggitarius and Pisces
Musical note: Re
Chakra: Svadhisthana (genital)