The tiny rock, known as MM40, is the first achondritic basaltic micrometeorite ever found on.    From Wordnik.com.  [Universe Today] Reference

In the scenario of a 1 - to 2-km diameter achondritic, PGEs-poor projectile exploding into the atmosphere or hitting only the Laurentide Ice Sheet, a crater would possibly not have been formed.    From Wordnik.com.  [Anthropology.net] Reference

Alternatively, to avoid PGE enrichment, it is possible to invoke the impact of one or several differentiated, PGEs-poor, possibly still unknown type of achondritic meteorites that vaporized in Earth's atmosphere at the BA/YD transition is one possibility.    From Wordnik.com.  [Anthropology.net] Reference

In the case of one or several surface impact (s) of achondritic projectile (s), which could explain the absence of PGEs in the studied BA/YD sections, it becomes difficult to explain the formation of nanodiamonds without a well-dated surface expression of one or several craters.    From Wordnik.com.  [Anthropology.net] Reference