Table 1. Presolar grains in meteorites.

Mineral	Year of discovery	Size	Abundance*	References
Diamond	1987	Average: 30 nm	∼500 ppm	5,7,23)
SiC	1987/1988	Mostly <1 μm, up to 50 μm (rare)	5.9 ppm	7)
Graphite	1990	>1 μm	0.88 ppm	7,24)
Refractory carbides (as subgrains)	1991	Up to a few hundred nm	(Present in host graphite/SiC grains)	21,25,26)
Oxides	1994	Mostly <1 μm, up to a few μm	1–3 ppm**	13–15,22,27)
Si3N4	1995	Up to a few μm	A few ppb	12)
Silicates	2004	<1 μm	29–57 ppm**	17–19,22,27)

* These numbers are relative to bulk samples of undifferentiated chondrites. The abundances of diamond, SiC and graphite are those in the Murchison meteorite (CM2). ** 100–200 ppm of silicates+oxides are a matrix-normalized abundance.²²⁾ In CO and CR chondrites where many of the abundance data have been obtained, the matrix comprise 30 vol% and 30–50 vol% of meteorites, respectively.²⁸⁾ Taking 30 vol% for the average and assuming that the matrix and the rest of the meteorites have the same density, the abundance of silicates+oxides relative to a bulk meteorite would be 30–60 ppm. The average ratio of silicates to oxides in CR chondrites is 22.²⁷⁾