Mysql process takes 500 mb of primary memory
You can get exact memory allocation of any process with a quick command:

sudo sysdiagnose PID


(Where PID is the process ID of the mysql binary or the name of the mysql process you want to inspect deeply). There is a manual page and you will want to start with vmmap.txt and all memory files. I'm not certain that 500 mb of allocation is a problem or even of concern without understanding the options you have configured for the database and what the rest of your workload is.