French Volcanic Clay Kills Antibiotic-Resistant MRSA Superbugby David Gutierrez(NaturalNews) Researchers have discovered that a clay made from volcanic ash in France has powerful antibiotic properties and is capable of killing even antibiotic-resistant superbugs such as methicillin-resistant Staphylococcus aureus (MRSA).it is fascinating, said researcher Shelley Haydel, a microbiologist at Arizon