Here’s another ‘souvenir’ acquisition I made in Japan – these from a hardware store called Tokyu Hands in Tokyo. (I have a little thing for pure metal objects or ingots). The cubes and cone casts are made of brass*, pure copper and pure aluminum. I think these are made available for science class in schools, more than anything else. There was a pure lead ingot for sale as well, but lead is poisonous and I did not want that in my house.
*Brass is basically an alloy of copper and zinc. Some types of brass alloys have small amounts of tin, aluminum, nickel or iron added in as well.