Author notes

Son of Mr. & Mrs. Rockhound 92

KAM

on March 2, 2018

As a general rule of thumb that's accurate. All three are silicon dioxides, but then so are opals, obsidians, and quartzes, but they have other visual differences.

Technically agate should have a cryptocrystalline structure, but that's a more recent discovery and back in the old days some people would call a stone an agate, because agates sold better than jaspers.