The diamonds that occur furthest to
the north, as those discovered in 1829 at 58 degrees lat., on the European
slope of the Uralian Mountains, bear a geognostic relation to the black
carboniferous dolomite of Adolffskoi* and to augitic porphyry, although more
accurate observations are required in order fully to elucidate this subject.
[footnote] *Rose, 'Reise nach dem Ural', bd. i., s. 364 und 367.
Among the most remarkable phenomena of contact, we must, finally, enumerate
the formation of garnets in argillaceous schist in contact with basalt and
dolerite (as in Northumberland and the island of Anglesea), and the
occurrence of a vast number of beautiful and most various crystals, as
garnets, vesuvian, augite, and ceylanite, on the surfaces of contact between
the erupted and sedimentary rock, as, for instance, on the junction of the
syenite of Monzon with dolomite and compact limestone.
[footnote] *Leop. von Buch, 'Briefe', s. 109-129. See also, Elie de
Beaumont 'On the Contact of Granite with the Beds of the Jura', in the 'Mem.
Geol.' t. ii., p. 408.
In the island of Elba, masses of serpentine, which perhaps nowhere more
clearly indicate the character of erupted rocks, have occasioned the
sublimation of iron glance and red oxyd of iron in fissures of calcareous
sandstone.
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