Oracle Delphi Acrylic mat - Madrigal cartridge?

I just bought an Oracle Delphi MK III that came without a mat for the platter. How do I find one of these or is there one for sale among the audiogon crowd? The turntable has a dark brown or black cartridge with a big M on the front already. I don't know what brand of cartridge this is? My friend thinks this might be an old Madrigal cartridge. I need to set my phono stage properly and want to find out about its spec's, etc. What do you know about this cartridge? Any help would be appreciated.