Having collected stromatolites in several locations in New York and Ontario, I was attracted to a small polished piece offered this past October by a dealer at the Rochester Gem and Mineral show. It was labeled Kabamba Jasper – stromatolite, Madagascar. It was a pretty green color, showed physical characteristics of a stromatolitic origin, and best of all, it was reasonably priced. I bought it and came home to research the geology and age of my new find. Immediately, things got complicated.
Bruce Leis has been an enthusiastic collector and researcher of stromatolites for over two decades. He has visited them worldwide, photographing their distinctive patterns and studying their geologic setting. In 2015 he teamed up with retired professor Bruce Stinchcomb and paleo-artist Terry McKee to produce a unique book detailing these wonderful and important geologic features. Anyone interested in earth’s geologic history and the development of life on this planet should enjoy their wonderfully illustrated 176 full page size treatise.
OK. Admit it, you thought this would be a note about the spectacular doubly terminated clear quartz crystals hiding in vugs in dolostones. Referred to as Herkimer diamonds, and known to mineral enthusiasts from across the country simply as “Herks” there has sure been enough written about them to last a lifetime. And goodness knows we all like to travel to Herkimer County to collect them. But no, this is not just another article about quartz.
Stromatolites are bio-chemically supported structures formed in shallow water when microscopic cyanobacterial material (formally known as blue-green algae) acts to bind and eventually cement sedimentary grains into what are essentially microbial mats. Changing climatic conditions, water depth, sediment influx, or the biology of the micro-organisms themselves leads to finely layered biochemical accretionary structures.