, are never, or almost
never, found in solid rock, but in loose earthy layers. In such
layers in Ceylon the abundance of precious stones, that is to say,
of minerals which are _hard, translucent, and strongly lustrous_, is
very great, and enormous sums would be obtained if we could add up
the value of the mass of precious stones which have been found here
for thousands of years back. Already Marco Polo says of Ceylon: "In
ista insula nascuntur boni et nobiles rubini et non nascuntur in
aliquo loco plus. Et hic nascuntur zafiri et topazii, ametisti, et
aliquae aliae petrae pretiosae, et rex istius insulae habet pulcriorem
rubinum de mundo".

But some one perhaps will ask, where is the mother-rock of all these
treasures in the soil of Ceylon? The question is easily answered.
All these minerals have once been imbedded in the granitic gneiss,
which is the principal rock of the region.

In speaking of granite or gneiss in southern lands, or at least in
the southern lands we now visited, I must, in the first place, point
out that these rocks next the surface of the earth in the south have
a much greater resemblance to strata of sand, gravel, and clay than
to our granite or gneiss rocks, the type of what is lasting, hard,
and unchangeable. The high coast hills, which surround the Inland
Sea of Japan, resemble, when seen from the sea, ridges of sand
(_osar_) with sides partly clothed with wood, partly sandy slopes of
a light yellow colour, covered by no vegetation. On a closer
examination, however, we find that the supposed sandy ridges consist
of weathered granitic rocks, in which all possible intermediate
stages may be seen between the solid rock and the loose sand. The
sand is not stratified, and contains large, loose, rounded blocks
_in situ_, completely resembling the erratic blocks in Sweden,
although with a more rugged surface. The boundary between the
unweathered granite and that which has been converted into sand is
often so sharp that a stroke of the hammer separates the crust of
granitic sand from the granite blocks. They have an almost fresh
surface, and a couple of millimetres within the boundary the rock is
quite unaltered. No formation of clay takes place, and the
alteration to which the rocks are subjected therefore consists in a
crumbling or formation of sand, and not, or at least only to a very
small extent, in a chemical change. Even at Hong Kong the principal
rock consisted of granite. Here too the surfac