The hardness of the lignite found in the Kimberley mine varies from that of soft charcoal to that of calcite, with which mineral it is mostly impregnated; the deepest being the hardest on account of containing more lime, and having undergone a greater change. It has been found in various parts of the mine, and at different depths. It has been also found in all the other mines, and in several instances large portions of stems, branches and roots were discovered. A specimen from De Beers mine was as hard as flint, but still retained its black color. In a specimen of a supposed root from De Beers mine the cells were square, instead of being circular, as in the figure.
I may here observe that “fossilized wood,” looking much like chalcedony or agate, is plentiful all over South Africa, and in the “Bush” (forest) of the Boston saw-mills, in Natal, not far from the river Umkomaas, inland to the north of Pietermaritzburg, whole stems of gigantic fossilized trees are to be found—and of the hardness of silex lying upon the ground. So far as I am aware the whole of such specimens are identical with the lignite of the Kimberley mine, thus tending to show that at one time this vast continent was/covered with forests of gigantic pine trees. The question at once arises, what has become of those forests? Have they been turned into coal in the place where they grew? or have they been washed into an ancient ocean and thus transported to some distant place? I think the answer must be that the greater portion have been washed away, and the remainder, the extent of which it is impossible to estimate, turned into coal and silicated wood, in, or nearly in situ. Fossil botanists will notice with interest the absence of distortion in the cells in the section delineated above, as evincing the fact that they have not been submitted to any great pressure.
Many of the specimens when found exhibited very evident signs of having been much rolled about and water worn, by their rounded ends, and the absence of attached branches, twigs, bark fruit and leaves, none of which have been found but the stems, larger branches and roots, with the exception of a portion of bark on the piece of the stem from which the above section was taken.
I must here draw the attention of my scientific readers to the great similarity to the section here depicted, and to a similar section of Greenland coal, as figured in the “Micrographic Dictionary,” 3d edition, 1875. The only apparent difference is in the slight distortion of the cells in the coal from Greenland.
Fig. 2. This shows a vertical radial section of the same lignite as that of Fig. 1, and drawn upon a slightly smaller scale, and by the same means, by Mr. Lee.
Diameter of pits or glands, rather less than ¹⁄₁₀₀₀ an inch, or ¹¹⁄₁₂ of ¹⁄₁₀₀₀ = .000916 of an inch.
Centre bright spot of gland ⅔ less than the gland.
The above section shows a single and double row of glands, by means of which Mr. W. Carruthers classifies this lignite as being derived from recent pines. (For Mr. Carruthers’ report and that of other authorities of the British Museum, see end of this section.) I may here state that I have seen many very beautiful sections of coal made by Mr. G. J. Lee, obtained by him from various parts of the Cape Colony and the Free State, and they all more or less show the single and double row of pit arrangement, the only difference being that the pits or glands are much smaller, as are also the tubes.