I went to the range this past Monday to shoot a couple of pistols. I fired 50 rnds of Aguila FMJ through a PT1911 I just picked up. The pistol was used and the original owner told me he only put about 100 rnds through it (I believe him too, the pistol looks to be in great shape).
I performed a detailed strip on the pistol before taking to the range. Today I decided to clean it after firing. Look what I found.

Why would this have happened. Is the extractor a MIM part? Any recommendations on a replacement extractor? Sucks...
After firing:
Cracked Extractor: