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EPIDOTE. 309 the varieties containing a large quantity of oxide of iron melt rather more easily; the varieties containing a large quantity of oxide of manganese melt readily into a black glass. With borax the green and black varieties yield a green glass ; the blackish- red varieties a glass which is violet in the outer flame, and colourless in the inner flame. In powder after fusion or igni tion is decomposed by hydrochloric acid, forming a jelly of silica. By ignition the specific gravity of epidote from Arendal is reduced from 3 403 to 3"27l. Ca 3 Si J + 244-Si, where part of the Ca is replaced by Mg, Fe, Mn, and e is ai, Fe or Sin. Several varieties from the north of Europe contain a small quantity of oxide of tin; epidote from Orrijerfvi contains nearly 1 per cent. Analyses of epidote a from Arendal, b from Eothlaue near Gutannen in the Haslithal, o = 3‘387, both by ltammelsberg, c from Geier in the Erzgebirge, d dark-green from Daupliine, e from Benig, f from Arendal, all by Kuhn :— a b c d e / Silica .... . 37'98 44-60 40-67 39'85 38-64 36-68 Alumina . . . 20-78 23’72 14-47 21-01 21-98 21-72 Bed oxide of iron . 17-24 8'33 1344 10-01 17-42 16-72 Eime .... . 23-74 24-71 30-00 22-16 21-95 23-07 Magnesia . . . I'll — 2’76 030 0-27 0-53 Analyses g of blackish-green epidote, G = 3"49, from Arendal, h from Burowa south of Miask, g = 3'35, i olive-green, g = 8'38, from Bourg d’Oisans, k grass-green, G = 3'39, from Ach- matowsk, I black, g = 3'6l, from Achmatowsk, m green, g = 3'33...3'34, from Achmatowsk, all by Hermann :— Silica . . . Alumina Bed ox. iron Erotox. iron Eime . . . Magnesia Soda . . . Garbonic acid AV ator . . 9 h i Jc I ill 30-79 30-87 37-00 37-38 . 36-97 36-45 21-24 18-13 18-57 18-25 21-84 24-92 12-90 14-20 13-37 1231 10-19 9-54 5-20 4-60 6-55 2-20 919 325 21-27 21-45 21-19 24-72 21-14 22 45 — 0-40 1-40 0-39 — — 0-08 — 0-91 — — 2-31 0-89 1'22 1-61 0-32 2'73 0-55 0-67 0-40 0-69 0-08 0-77 A contains also soda 0'08 and traces of boracic acid, k traces of boracic acid.
