So i might just be stupid and doing it wrong but I downloaded the launcher logged on and it starts up until the black screen then quits and i get this at end that says

Client> Invalid memory access of location 0x0 rip=0x0
Client>
Game ended with bad state (exit code 139)
Deleting /Users/alisafaye/Library/Application
Support/minecraft/version/1.5.2/1.5.2-natives-1372338907477405000

so yeah if anyone knows feel free to help me out, thank you