| Although blue corundum, zircon, and tourmaline occur in Colorado, they are not known to produce gems. |
| Also on a hillside to the north is a contact metamorphosed bed rich in small, dark blue, platy corundum crystals. |
| Reports of gem-quality corundum are rare in Wyoming, although both ruby and sapphire have been noted. |
| Chapters 2-19 describe eighteen specific traditional gemstones or families, beginning with corundum and ending with rhodonite. |
| He also found particles of gemstones such as corundum, garnet, rutile, and argentite. |
| The grayish-blue, partly gemmy cordierite, when first discovered in the early twentieth century, was mistakenly reported as corundum. |
