ABSTRACT

To come to an understanding on the origin of ball coals the orientation, sphericity, roundness, chemical and petrological compositions of ball coals have been studied.

A study of the orientation of the ball coals has established a close association between the long axes (a) of the ball coals and the joints of the coal seams in which the ball coals are found. From this association it has been concluded that the joints in the coal seams formed rectangular blocks of coal which were later transformed into ball coals. Further study of the sphericity and roundness of ball coals has corroborated the above conclusion. The relation of the long axes of the ball coals with the sphericity and roundness has shown that reduction in the size was associated with an increase in both the sphericity and roundness.

Chemically and petrographically the ball coals are similar to the coals in which they are embedded. This suggests that the ball coals were derived from the parent matrix coal.

It has been concluded that mainly due to curved jointings, produced as a result of heat alteration, the transformation of a block of coal to the form of a ball coal took place.