Well, here's what Atomica said:

WORD HISTORY The origins of the word tin may date to a time before Europe had been settled by speakers of Indo-European languages, such as the Germanic and Celtic languages. Related words for this metal are found in almost all Germanic languages, such as German Zinn, Swedish tenn, and Old English tin (as in Modern English), but no other Indo-European language family has such a word. This fact suggests that the word tin may have been borrowed into the Germanic languages from a pre-Indo-European language of Western Europe. This possibility is supported by the Bronze Age importation to the Near East of tin and copper from Europe, where the metals were produced and metal objects were manufactured. Lest we be too amazed by this accomplishment, we might remember another remarkable achievement of pre-Indo-European society, the construction of huge megalithic monuments such as Stonehenge.

It's interesting but doesn't really answer your question. But now we know that tin has very old roots!