The Coquet.—Blindburn.—A dark-grey compact rock with an irregular fracture. A few small scattered felspars may be recognized. Red streaks and blotches occur. Under the microscope two generations of felspar may be recognized; the larger porphyritic crystals abounding in inclusions of the ground-mass of the rock, while the smaller and later crystals are comparatively free from inclusions. Both kinds are somewhat altered, small portions here and there showing aggregate polarization, while the main mass of the crystals gives definite extinctions. The pyroxene has almost entirely disappeared. Sections of characteristic form may however be distinctly recognized. These are now principally occupied by an aggregate of quartz granules or a mixture of quartz and chalcedony; but here and there fibres of a brilliant and peculiar green mineral occur scattered throughout the quartzose aggregate, and these doubtless are an alteration product of the original pyroxene. Iron oxides are comparatively rare in this rock. The ultimate base is a brownish isotropic and minutely granulated substance. Under the highest power at my command (1000 diameters) the granulation cannot be resolved, and I am therefore not able to say that any clear homogeneous glass is present. Veins containing quartz and calcite occur in the rock.