a vitreous lava, whence its old name, " lava-glass," was called after a
certain Obsidius or Opsius, who first discovered it in Ethiopia (xxxvi.
67). " It is extremely black and sometimes translucent (in thin
pieces), and, inlaid in chamber-walls in the form of mirrors, it
reflects shadows instead of images." By a strange coincidence, the
Peruvians, when first discovered, had Obsidian (Itzli) mirrors in
general use. One of these Obsidian mirrors seems to have found its way
to England, and to have been converted into the identical " black stone
into which Dr. Dee did call his spirits :" for so it is described in
the Peterborough Catalogue. It had been long, probably since the
conjuror's death, in the possession of the Mordaunts ; after other
changes of owners, in Horace Wal-pole's ; and now is in the
Londesborough Collection. The strange shape to which the stone is cut
betokens an Aztec origin. This may dispute with the crystal sphere,
already noticed, the honour of being the instrument used by Kelly, Dr.
Dee's coadjutor ; whereof Butler :—
" Kelly did all his feats upon , The Devil's looking-glass, a stone ;
Where, playing with him at bopeep, He solved all problems ne'er so deep."
persons (adds Pliny) make signet-stones out of it." This fashion does
not seem to have lasted long, for antique intagli in Obsidian are
extremely rare. There was, how-(g)