(1) As previously reported, supplementary descriptions of the previous paper (part 4) regarding the geographical distribution and occurrence of the diatomaceous earth in Japan, especially the details of actual survey accomplished by the auther on several deposits located in the North-eastern provinces of the country are described in this paper.
(2) The Tertiary deposit which has been probably formed by the weathering of a bed of diatomaceous shale are found in the region along the coast of the Japan Sea, namely in Aomori and Akita prefectures (Takada-mura, Higashitsugaru-gun; Shimizu-mura, Kitatsugaru-gun, Aomori-ken; and Tsuzuriko-mura and Yonaizawa-cho, Kitaakita-gun; Kitaura-cho, Minamiakita-gun, Akita-ken).
Their deposits occur as massive slaty beds and outcrop at top and side of the low hills as creamcolored beds showing a conchoidal fracture. The earth almost entirely consist of the fragments of the diatoms of marin origin type “Coscinodiscus”, admixtures of spicules of sponges and other impurities.
(3) The Quarternary earth that occur as stratified layers are found in Aomori, Miyagi and Fukushima prefectures (Ofukanai-mura, Kamikita-gun, Aomoriken; Enda-mura Katta-gun, Miyagi-ken; and Okinagima-mura, Yama-gun, Fukusima-ken).
Of those the most important are those located near Enda-mura, Katta-gun, Miyagi prefecture. Their deposits are well known as most valuable beds in Japan. The horizontal strata of the diatomite with 2m. in average thickness are interbedded with very extensive overburden of sand stone and agglomerate ranging from 10 to over 25m. in thickness. The high grade earth from here is low density without impurities and consists of mainly large and well preserved circular diatoms of fresh water types, including “Cyclotella and Stephnodiscus” simillar to those of Okayama and small cylindrical “Melosira”.
(4) Many photographs showing occurrence and minning operation of their deposits and microphotographs of several earths are also illustrated in this paper.
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