What are the P-type asteroids made of?

Abstract

The P-type asteroids, together with the D-type asteroids, used to be believe to be more primitive than any known carbonaceous chondrites and would not come to the Earth as a meteorite. Because the P asteroids fall in between the C/G/B/F asteroids and the D/T asteroids in reflectance spectral property and radial distribution around the Sun, now that the Tagish Lake meteorite fell and turned out to be possibly from a D or T type asteroid, it is natural to believe that the P asteroids are made of materials intermediate of the thermally metamorphosed CI/CM chondrites and the Tagish Lake meteorite.