The lower part of the Pliocene sediments in the Naegi district, Gifu Prefecture, is rich in commercial clays such as 'gaerome' clay, 'kibushi' clay, and white clay, which are considered as fresh-water sediments in small basins on granite.
The present writers have carried out field observation of geological occurrences of the sediments and mineralogical study of the clays by means of X-ray diffraction, electron microscopy, and optical examination.
The clay fractions of the 'gaerome' and 'kibushi' clays are mainly composed of platy crystals of kaolinite accompanied by illite and tubular halloysite. The 'gaerome' clay contains coarser grains of quartz and potash feldspar and the 'kibushi' clay, as well as the larger part of the 'gaerome' clay, is stained dark brown by organic substances. The basement granite, which is considered as the source material of the overlying 'gaerome' and 'kibushi' clays, is weathered and the feldspar is altered. mainly to halloysite with the shape of long tube. Based upon the difference in mineralogy between the 'gaerome' and 'kibushi' clays and the weathered granite, the writers concluded that halloysite was transformed into kaolinite in the course of transportation and deposition of clays.
The white clay is an alteration product of pumice. It is usually composed of spherical or tubular halloysite, although it consists of kaolinite in some cases. This difference in mineralogy seems to be related to the length of time elapsed since the alteration.

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The Kamikita mine is located in the central part of the Aomori Prefecture, about 36 km southwest of Aomori City. Ore deposits of the mine are well known as one of the representative ore deposits of "Kuroko" type. The mining area occupies a northern part of the Tohoku Green Tuff region where no exposure of the pre-Tertiary basements has been found. The area is composed of the Tsubokawa, the Okunosawa and the Kotsubogawa formations of the Miocene in ascending order, and Quaternary formations of the Old Hakkoda volcanics which unconformably cover the Miocene formations. The Okunosawa formation consists mainly of rhyolite domes and lavas with related tuff breccias. Rhyolitic volcanic activity of the Okunosawa formation is divided into two stages ; older and younger. Five ore deposits have been found only in the Okunosawa formation.
The Daisan Shitaban Hi ore bodies which belong to the lower ore body group of the Kaminosawa ore deposits are divided into two groups based on their modes of occurrences and geneses. The first group consists of the bedded compact sphalerite-rich ore body (so-called "Kuroko" ore body), the bedded compact chalcopyrite-rich ore body (so-called "Ohko" ore body), the massive pyrite ore body (so-called "Ryukako" ore body), and the stockwork ore body in descending order. Arrangement of these bodies show vertical zoning found in the "Kuroko" deposits. These are considered to be primary in origin. The second group is composed of the bedded fragmens bearing ore bodies with various. ores and lithic fragments. Judging from the lateral and vertical size grading, sole marking and orientated arrangement of elliptical boulders found in the ore bodies, and their texture and mineralogy, it is concluded that the second group was formed by the sedimentary deposition of the ores of the first group due to the submarine sliding or the mud flow caused by the volcanic explosion in the later stage of the Okunosawa volcanism.

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The Kamagamine "Roseki" mine, located in the western part of the Shokozan district, produces about 2, 500 tons of "Roseki" monthly, as a raw material for refractories, paper-clay, tiles and crucibles.
Terrigenous volcanic rocks of the Cretaceous age, interposing fine grained tuff, tuffaceous shale and shale, are distributed extensively around this mine.
The stratigraphic sequence is as follows :
Upper
Lower
Dikes: Quartz porphyry and porphyrite.
Granitic rocks: Biotite granite, granite porphyry and quartz-diorite porphyry.
Rhyolitic tuffs: Rhyolitic crystal tuff, lapilli tuff and welded tuff.
Dacitic tuffs: Dacitic tuff breccia, lapilli tuff, welded tuff, fine tuff, shale, tuffaceous shale and volcanic conglomerate.
Andesites : Andesite lava, andesitic tuff and dacite lava.
The hydrothermally altered zone, which is mainly composed of pyrophyllitized, silicified and sericitized rocks, occurs in the dacitic lava and dacitic tuff beds. The "Roseki" deposit, consisting of pyrophyllitized and silicified rocks, is concordant with the bedding of the wall-rocks, at the near surface part, while, at the deeper part, it sometimes occurs in pipe-and vein-like shapes cutting the bedding of wall-rocks of host formations.
The "Roseki" deposits are believed to. have been formed immediately after the deposition of the dacitic tuffs.
The main constituent minerals of "Roseki" clay are pyrophyllite, quartz and sericite, and accesories are diaspore, boehmite and kaolinite. The mineral assemblages of pyropyllite-quartz and pyrophyllite-sericite-quartz predominate, while meager occurrences of pyrite and hematite are noted in the clay.

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