CompuServe Messages

Hi, Bill– Welcome to the forum! Numbers I had earlier jotted down from the Encyclopedia Brittanica tell me for the continental crust (which should be much the same as the top 50 feet) that the commonest by weight % of oxide (thus oxygen is high on the list, but I do not know exactly where to place it) are silicon (57%), aluminum (16%), iron(9%), calcium(7%), magnesium(5%), sodium(3%), potassium(1%), and titanium(1%). For ocean crust, the order is the same, with silicon less in proportion (but still 1st) and the others more, while calcium noses out iron for 3rd. Many of these are in tight chemical combinations that make them not easily extracted. Titanium, for example, is common, but not used a lot because it costs a lot of energy and effort to bust it out of even its best ores. But given fusion power, dropping ordinary rock into a fusion torch and extracting even the toughest customers may become easy someday. –Doug