Subject: Will the mini black hole be bigger or smaller then the ones forming now?

Mini black holes according to one branch of string theory scientists form when 
the high energy cosmic rays strike the atmosphere, assuming that the theory is 
correct gravity becomes a stronger force when extra demensions are involved. I 
really want to know whether this is true for high energy cosmic rays striking 
solid bodies, can that create mini black holes as well, and if high energy 
cosmic rays can make mini black holes of about 10 micrograms when they strike 
Earthe's atmosphere, so will high energy cosmic rays striking a metalic or a 
rocky asteroid create a more massive, or a less massive mini black hole given 
that the obect's density is greater and the atomic mass may be greater?

I am asking because I want to discuss it with my professor, my professor is 
very interested on this issue 

Re: Will the mini black hole be bigger or smaller then the ones forming now?