Thogchags [Tibetan: ཐོག་ལྕགས] are tektites and meteorites which serve as amulets. Typically high in iron content, these are traditionally believed to contain a magical, protective power comparable to Tibetan dzi beads. Most thogchags are made of a copper alloy.
A popular Tibetan belief is that thogchag are produced magically when a thunderbolt strikes the earth. Historically, it was believed that if one was to find a thogchag underground by chance, they would work as a good luck charm.
There is a great similarity between protective plaques and thogchags, because both protect the owner. The difference is that thogchags have an eyelet and so can be worn on the neck with a string. Protective plaques do not have an eyelet and are worn in clothing or even in pockets.