• journal_title：Economic Geology
• Contributor：Harrison Ashley Schmitt
• Publisher：Society of Economic Geologists
• Date：1950-
• Format：text/html
• Language：en
• Identifier：10.2113/gsecongeo.45.1.54
• journal_abbrev：Economic Geology
• issn：0361-0128
• volume：45
• issue：1
• firstpage：54
• section：Articles

Construction of the ideal vein with the assumption that the theory of uniformitarianism applies throughout Earth history is questioned. Certain data suggest that some types of mineral deposition may be unique with time. Data given by Jeffreys and Daly strongly indicate that the Earth and particularly the Earth's crust has changed fundamentally with time. Present day theory implies that vertical zoning of genetic types should be common; actually it is rare. This suggests the need for competing hypotheses of "mineralization" genesis. The depth classification of mineral deposits by metal content is unsatisfactory. For example, Tertiary deposits of epithermal character contain commercial deposits of metals which would normally be said to be characteristic of the "deep zone." Although the majority of elements seem to persist in the various ore mineralizations throughout Earth history certain ones may be quantitatively unique with time. Mercury, selenium and tellurium seem characteristic of late time. Sulphur chemically related to the last two elements seems to have been unevenly distributed in early time. Another chemical group, bismuth, arsenic and antimony may be characteristic of late time.