Forsterite with less than about 2% FeO in the carbonaceous (C3V, C3O, C2) and unequilibrated ordinary chondrites (UOC) shows cathodoluminescence (CL) hues ranging from red to purple to blue. Spectral scans of the light show that it is composed of two broad peaks for forsterites in the C3V, C3O, and UOC meteorites, one centered at about 458 nm (visible blue) and the other near 800 nm but extending into the visible red. The resulting color varies with relative intensities of the two peaks. CL of forsterite in C2 meteorites is distinctly different with a broad weak peak in the blue and a broad peak at about 723 nm in the red. These distinct spectral differences should allow a rapid method of assigning single forsterite grains such as those in deep-sea particles or in cosmic dust to a particular source or affinity.

Blue CL correlates with a high level of refractory minor elements including Al, Ca, Ti, and V, whereas red CL correlates with high Mn and Fe. Cr shows no obvious difference between the two colors. Scanning CL allows recognition of dramatic and complex textural features associated with these forsterites.

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