Their origin and formation. 123
similar
protuberance in the same position was noticed. Again the cold chisel
was resorted to, and again a large Pearl was found. This time, however,
although perfectly round and the size of a large solitaire marble, it
had come within reach of the advancing decay of the shell ; one third
of an inch was rotten, and after its weight was reduced from 84 to 45
grains, a round slate coloured Pearl was obtained, but of little value.
A year previously this Pearl might probably have been found perfect,
and have been worth say from £2000 to £3000. It is worthy of remark
that when decay reaches the lower point of an embedded Pearl, it
spreads upwards around the Pearl, aided apparently by the upward
tendency of the layers of the blister, and eats into it, at an almost
equal rate all round.
In 1882 the "Harriet" was fortunate enough to
find a Pearl, weighing 103 grains, within an enormous blister. It was a
beautiful bouton, of fine colour on the top, but somewhat chalky
beneath, owing to the contact of salt water admitted by a "borer," that
had chanced to pierce the shell just at this spot, and had penetrated
nearly i of an inch into the Pearl.
In 1885, the "Ivy" found a Pearl in the lips of a small-sized shell, whilst fishing in Exmouth Gulf.
