Aztec pyramids

Mexico City is built on the site of the original Aztec capital, and some of the Aztec structures are still preserved. Most notable is the Pyramid to the Sun, in the Aztec city of Teotihuacan.

The ring I mention was a sterling silver ring with a black obsidian in the shape of an Aztec mask. Obsidian is a volcanic stone, and Mexico City is directly on the "Ring of Fire", the edge of the Pacific tectonic plate where most of the world's volcanos are located. It isn't surprising that obsidian is easily found there, nor that the Mexicans use it extensively in their costume jewelry. They are also excellent silversmiths... but let's leave that for next week.

In case anyone isn't convinced of the volcanic activity in the area: