OCR Text |
Show 56 from one to several feet and have a length of 10 to 20 times the diameter. Some rolls are covered on one Side only with ore extending along the sandstone bedding on the opposite side. Rolls of ore are found alone and in close association with a tabular deposit at the margins, along the top, or enclosed in the main ore body. A few of the larger rolls are as much as 60 feet long and more conspicuously elongate than the more numerous small rolls. Where the long directions are well developed a parallel orientation is common. The tabular deposits also have many variations. Their size range is considerable, some containing only a few tons and other many thousands of tons of ore; most of them, however, yield only a few hundred to 1,000 tons. The boundaries vary from a well-defined contact to an unr-even and gradational limit. As a rule the most regular mineralization is in thin, persistent beds along which local, thick lenticular ore bodies are found. Ore bodies ith the less regular limits are usually the largest. In the Club group of mines a series of tabular deposits.have been developed and mined over a lineal extent in excess of 3,000 feet from northeast to southwest; at right angles the ore bodies were 300 feet in extent. The ore boundaries varied from well defined to less definite contacts and show close relation to the cross-bedding. Another variety of vanadium mineralization is related to fossilized tree logs. The logs range In diameter from a w |