A list of the solid substances of the earth making up the so-called lithosphere (or rock sphere) in order of their abundance, does not at all correspond to a list made in order of commercial importance. Some of the most valuable substances constitute such a small proportion of the total mass of the lithosphere that they hardly figure at all in a table of the common substances.

RELATIVE ABUNDANCE OF THE PRINCIPAL ELEMENTS OF THE LITHOSPHERE

When reduced to the simplest terms of elements the outer ten miles of the lithosphere consists of:[1]

PERCENTAGE OF PRINCIPAL ELEMENTS IN THE LITHOSPHERE

Oxygen47.33
Silicon27.74
Aluminum7.85
Iron4.50
Calcium3.47
Magnesium2.24
Sodium2.46
Potassium 2.46
98.05

The remainder of the elements exist in quantities of less than 1 per cent. None of these principal elements occur separately in nature and none of them are mined as elements for economic purposes.

RELATIVE ABUNDANCE OF THE PRINCIPAL MINERALS OF THE LITHOSPHERE

Minerals exceptionally consist of single elements, but ordinarily are combinations of two or more elements; for instance, quartz consists of a chemical combination of silicon and oxygen. The proportions of the common minerals in the outer ten miles of the lithosphere are in round numbers as follows:

PERCENTAGE OF COMMON MINERALS IN LITHOSPHERE

Feldspar49
Quartz21
Augite, hornblende, and olivine15
Mica8
Magnetite3
Titanite and ilmenite1
Kaolin, limonite, hematite, dolomite, calcite, chlorite, etc. 3
100