Some regard the eclogite boulders as derived from deep-seated crystalline rocks, others as concretions in the blue ground.
This is still more forcibly suggested by the remarkable eclogite boulder found in the blue ground of the Newlands mine, not far from the Vaal river, and described by T.
In both occurrences, however, there is still the possibility that the eclogite or the basalt is not the original matrix, but may have caught up the already formed diamond from some other matrix.
On the other hand many tons of the somewhat similar eclogite in the De Beers mine have been crushed and have not yielded diamond.
In a basic neck of this period at Inverell, there are eclogite boulders, containing diamonds in situ; and it is doubtless from these basic volcanic necks that the diamonds of the New England tableland have been derived.
In another eclogite boulder, diamond was found partly embedded in pyrope.