I am writing an essay on the origin of life and I was reading an article on hydrothermal vents. (Peptides by Activation of Amino Acids with CO on (Ni,Fe)S Surfaces: Implications for the Origin of Life).
It appears that (Ni,Fe)S has played an important role in protein synthesis, but I wanted to know more about the substance its self. It is a compound, a group of chemicals? Or is it simply nickel, iron, and sulfur individually? I'm not very clued up when it comes to chemistry and I haven't come across that sort of notation before.