Figure 22. Larger inclusions of beryl crystals formed by spontaneous nucleation are occasionally found, as in this type 2 example. The included beryl crystal exhibits a core with a high concentration of trapped flux particles and a clear rim. The boundary between the almost clear rim and the host is best seen under crossed polarizers. Transmitted light (left), with crossed polarizers (right). Photomicrographs by H.A. Gilg.