The next group of agates which I have to describe belongs to the nested series; but is distinguished from all other varieties of that series by having a pure chalcedonic surface (unaffected, except in the form of it, by the material of its gangue); and by uniformity of colour; consisting only of white and transparent grey bands, wholly untinged by more splendid colours. But nearly all the agates of this group which now occur in the market have been dyed brown or black at Oberstein, to the complete destruction of their loveliest phenomena.