MOUNT SORREL GRANITE.--The granite is of two varieties, red and grey, the difference being due to the fact, that in the red masses, the partially decomposed felspar has been coloured by ferric oxide. The rock is a hornblendic granite, the constituents being quartz, felspar, biotite, hornblende and titanite, with magnetite and a little apatite. The felspars are orthoclase and plagioclase; the former is much decomposed, while the plagioclase frequently remains clear, and exhibits well its twin striation. Biotite was originally abundant, but is very frequently replaced by a clear green substance, which is strongly dichroic, the two colours being grass-green, and clear yellow. The hornblende has been greatly decomposed; clear crystals are, however, not uncommon, and exhibit the usual optical characters of the mineral. The products of alteration are chlorite and epidote. The titanite appears in reddish-brown grains, but is not very abundant. In 1879, the writer discovered the junction of the granite with the sedimentary rocks, and proved that the former was intrusive (Geol. Mag. dec. ii., Vol. vi., p. 181). The junction occurs in Brazil Wood, where there is a small quarry, in which granite veins may be seen to penetrate the strata in various directions; a large mass of granite is also within a few yards. Some of the phenomena of _contact metamorphism_ may here be readily studied, the granite having converted the slate into a crystalline micaceous schist, quite similar in character to those produced under like conditions round the granite in Cornwall and elsewhere. Small garnets occur in the altered slates, and also in the granite close to the junction. THE CHARNWOOD SYENITES.--The Syenites and other igneous rocks of Charnwood, have been described by Messrs. Hill and Bonney (Quar. Jour. Geol. Soc. Vol. xxxiv., p. 199.) The original constituents are felspar, hornblende, quartz, apatite, ilmenite, magnetite and titanite. The felspar is of two kinds, orthoclase and plagioclase, the former is very turbid and decomposed, while the plagioclase is clear, and retains its usual optical characters. The curious intercrystallization of quartz and felspar, known as _micropegmatite_, is common in the masses of syenite near Groby; the best examples, however, have been found by the writer in the Markfield rock, where it appears to form a ground-mass in which the larger crystals of orthoclase and plagioclase are enclosed. A small portion of the hornblende is still characteristic, but the greater portion appears in various stages of decomposition; the alteration products being chlorite and epidote. Titanite is by no means rare, and occurs in well formed twin crystals.