Websterite

On Websterite found in the Plastic Clay of Auteuil, near Paris [article title]

Fig. 6 is the interesting spectrum of the bright blue compound of alumina. These three bands, although generally faint, are narrow and well defined, the blue and green spaces being invariably clear. Websterite and cryolite show this spectrum to great advantage.

Among some specimens of eruptive rocks obtained from Gallatin, Jefferson and Madison Counties, Montana, Merrill finds basalts, andesites, lamprophyres, syenites, porphyrites, wehrlites, harzburgites and websterites, some of which possess peculiar characteristics.