Corroded quartz grains present in sedimentary ores of iron and manganese are evidence of high pH. Other things being equal, the activity of iron and manganese necessary to cause precipitation is lower if precipitation occurs at a higher pH. Under conditions of high pH, it is possible that deposition of iron and/or manganese may have occurred from waters only ten times richer in these constituents than average near-surface sea water.

First Page Preview

First page PDF preview
You do not currently have access to this article.