10th Anniversary is Tin or Aluminum, according to the traditional anniversary gift list.
Although aluminum is an abundant element, it was actually an extremely costly material before efficient methods of extracting it were developed. In the early 1850s, it was still more expensive than gold! But as technology improved, production costs went down. Though a metal, aluminum is extremely lightweight. It has been used in everything from brightly colored martini shakers to lightweight chairs to soda cans.
Why both tin and aluminum? Most likely because both metals have a number of similar properties.. both are malleable metals, resistant to corrosion, and light grey in appearance. They are also (at least today) among the more basic metals rather than the precious ones. This makes sense from the standpoint of later anniversaries having more precious metals, such as silver for 25th and gold for 50th. Since this is the first metal chosen to celebrate a major anniversary year, it seems reasonable that a more common one was chosen. Though a common metal can still be made into a beautiful object...
The modern gift lists suggest a different material for the tenth wedding anniversary... diamond! Sparkling, lovely, rare, valuable, romantic... Diamonds speak for themselves, with all the symbolism easily appreciated.