| Some of the alumina and iron oxide may occasionally be chemically combined, so as to form an iron spinel, or hercynite. |
| Even the famous Black Prince Ruby in the British Imperial State Crown is actually a spinel, not a ruby. |
| Peridotite: magmatic rock of color green blacky made up of olivine, pyroxene and spinel with sometimes the presence of biotite and garnet. |
| It grades into a manganese-rich ilmenite that ultimately replaces the spinel phase near the transition to the garnet amphibolite. |
| New cross-sectional electron microscopy has yielded a threshold energy loss value of fission products for amorphisation of spinel. |
| Some of the characteristic minerals found in kimberlite are perovskite, magnetite, and spinel. |
