THE IMPORTANCE OF QUARTZ 117 



Clays may have been important in two ways. The extremely small 

 size of the individual grains results in a very large grain surface by 

 weight of a clay sample. This enables strong adsorption on these 

 surfaces of the various compounds of the 'thin soup'. Moreover, the 

 clay crystal lattice forms miniature piles for any diffusing process 

 transversely to its parallel layers. Just as the piles in technology, 

 they might have accentuated differentiation processes. Differential 

 diffusion of a very minor value through a single layer may have 

 become important when summed up over the entire crystal, small as 

 they are. 



Differential adsorption of the surface of clay grains and differential 

 diffusion through cr\'stal lattices forming its miniature piles con- 

 sequently may have been significant in the early days of inorganic 

 photosynthesis. Of course, we do not know of such processes, but 

 because there is a fair probability that they have occurred somehow, 

 it is well to remember that clays were abundant at that time. 



THE IMPORTANCE OF QUARTZ 



A similar case is presented by the common mineral quartz, which 

 forms the grains of almost all sands now. Although in the early 

 atmosphere other sands were present, as we saw in the preceding 

 chapter, quartz was a very common mineral too; already in the 

 earliest time of the geologic history. The importance of the prevalence 

 of quartz on the surface of the earth lies in the fact that all present 

 living matter is optically active. This fact, first discovered by Louis 

 Pasteur, has since been confirmed by all later studies. 



Terent'ev and Klabunovskii (1960) and Klabunovskii (1960) pub- 

 lished papers on this subject in the Moscow Symposium, to which the 

 reader is referred for full information. Let it suffice to state here 

 that quartz, with its slightly asymmetrical crystal lattice, has an 

 optically active crystal surface. By selective adsorption of compounds 

 which have optically active molecules, but are inactive because the 

 latter are present on a fifty-fifty basis, optically active compounds 

 can be formed. In nature, however, there probably are as many 

 dextro-suridLces of quartz grains as there are laevo-surisices. Conse- 

 quently, the optical activity of quartz surface in itself is not sufficient 

 to bring about optical separation. There is a probability, however, 

 of a selective natural process operating on this interaction of early 



