The researchers have been examining weathered specimens of granite, rich in the mineral potassium feldspar. The surfaces of weathered feldspar crystals are honeycombed with tiny pores and channels of just the right size and surface chemistry to engender the earliest biochemical reactions. The traditional picture of lightning-fuelled chemical reactions in warm puddles is going out of fashion. More likely is the assembly of organic molecules on a surface - especially a catalytic surface, whose topography or chemistry might encourage biochemical reactions. Clays have been favourite candidates, because they easily adsorb organic molecules, and have a high surface area in relation to their volume, producing a lot of catalytic surface in a small space.
Catalytic surfaces are commonplace in industry.
The catalyst could be a powdered metal, or a zeolite, a natural or artificial mineral with a structure like Emmenthaler cheese - full of tiny holes and channels in which reactions can take place, reactions that might not happen at all in the energetic buffeting of open, free solution. Smith and colleagues propose weathered feldspar as a candidate for fostering early biochemical reactions. Feldspar is a common mineral and has been around as long as the Earth itself. Honeycombs in the mineral would have nurtured organic compounds such as amino acids and nucleotides, promoting their formation into proteins and nucleic acids, respectively. The honeycombs would provided access to impurities in the feldspar, rich in certain trace elements and phosphorus, essential for life.