Professional papers

by T.A. Rickard

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 ... and upbuilding, ever shifting their centers of activity but never at rest. In the latter part of the Tertiary period the basaltic lava found its passage through the fractures traversing the Silurian rocks and covered the golden alluvium lying upon their eroded edges. II. The Auriferous Quartz. The origin of the deposits of gold-bearing quartz, belongs to no » particular period. The agencies which brought the ore of the reefs to its present position began to operate when first the sediments of the Silurian seas were laid down, and have continued until now. In the reefs of Bendigo the two most important substances are, the metal, gold, and the matrix quartz. The other mineral constituents found in association with these two are relatively unimportant. Their origin is a matter of much interest but it can be discussed apart. 1. The Quartz. The Silurian sediments contained a large proportion of sand, and the resulting rocks are very siliceous. Silica occurs in the rocks partly in a free state, as quartz, but a proportionally larger amount is found combined as a silicate. Free quartz is soluble in heated waters. The quartz combined in the more complex form of silicates has been demonstrated by Daubree and others to be readily dissolved in hot water, more particularly superheated steam. The formation of the quartz lodes has taken place in two stages, namely, leaching followed by precipitation. In both operations water was a necessary factor. It is the all-powerful disintegrating and transporting agent of the land-surface, where its chemical activity is intensified by the presence of dissolved carbonic acid; it is also, though in a different way, no less efficient underground where by reason of the prevalence of a higher temperature it becomes more energetic ...

196 pages, Paperback

Published January 1, 2012

About the author

Thomas Arthur Rickard (1864-1953)