Abstract
The best molding sands available have usually been found only by a lengthy process of trial and error, but rarely by any scientific, espcially geological basis.
Of course the desiderata in prospecting for molding sands available is firstly to investigate the properties of them, i.e., the granularity of sands and the properties of bonding part as well as sand part which the writer has already looked into in the previous reports.
In this report, the geological origin and mode of occurence of molding sands of Japan were investigated by the mineral composition and the geological literature of the region of the product.
Then, an attempt was made to acquire the following desiderata in prospecting for molding sands in Japan by the collected data in this time:
(1) The most part of molding sand deposits in Japan are terrase deposits in the lower reaches of river (along present or abandoned lines of drainage) or marine deposits.
(2) They are, also, of diluvial or older alluvial age.
(3) The original rocks which are deemed to have furnished the best molding sands are: (a) quartz diorite, (b) plagio-liparite, (c) granite (in this case the acidic feldspar is required to be almost kaolinized), (d) sandstone (its mineral composition must be special and suitable for molding sands.)
