One of the Original 12 Minerals on Earth

Working around geologists, I just recently discovered that at the beginning of Earth's formation, there were only 12 minerals:  "The earliest interstellar material, including diamond, graphite, corundum [ruby, sapphire], and olivine [peridot]—a total of just 12 minerals."

http://earthdate.org/node/102

Today on Earth, there are over 4,000 minerals. Apparently, the minerals evolve and reproduce!

I was surprised to learn that one of the original 12, olivine, was currently available for purchase online. (How would something so rare be so available?) I bought some rough versions, for around $9 apiece. In their polished forms, they're "peridot," my August Leo birthstone. But I'm much more interested in knowing that, in whatever form, olivine was one of the first minerals, EVER, on Earth. The chunks, pictured below, that I bought for $9 apiece are over 4 million years old. I got a bargain!