Geosmin (if you can get it); smell of wet earth. Humus Absolute. Terrasol. Ethyl Amyl Ketone, and Amyl Vinyl Ketone, smell of mushrooms; fungal. Myrcene and ocimene smell metallic, harsh. Also try some of the straight chain aldehydes (C8, C9 and C10 especially). Ultrazure, and Rossitol, have a mineral, watery smell.