抄録
Many subspherical pyritic coal balls are found in the upper portion of the coal seam of Oyake 5-Shaku of the Omine colliery, Chikuho Coal Field. The authors have detected the distinct fossilized wood tissues from the polished specimens of those pyritic coal balls ; the wood tissues consist of the following parts.
a. Slender twigs of a conifer. They are present abundantly, and their original plant tissues are preserved nearly completely. They have no annual rings, so that they must be of a year wood, probably derived from fallen leaves of a tree having feather-like twigs such as common in those of Taxodium.
b. Half decomposed heart woods filling the interspaces of the above described twigs. These have distinct annual rings, consisting of tracheids. They have no vessel structure which is a determinative characteristic of broad-leaved trees, and, moreover, they are found to be similar to those heart woods of the silicified woods popular in the coal seams of the Chikuho Coal Field, and are determined to belong to Taxodioxylon sequoianum Gothan.
c. The interspaces of the woods structures are filled with structureless pyrite.
Presence of nearly or completely identical structures and components have been confirmed in the dolomitic coal balls from the Yubari and the Bibai coal seams of Hokkaido. All of these may suggest the original features of forest swamp of the coal-forming environments of Japanese coal fields.
