Dr. Davy on the Geology and Mineralogy of Ceylon . 319 
gneiss alluvion in Saffragam and Matura. Prase is a variety of 
quartz that is not common in the island ; I have only met with it 
among the pebbles on the sea shore at Trincomalie. The second 
species of quartz, iron-flint, is not uncommon in the Kandian 
country ; it is found in the beds of rivers, in the state of rolled 
masses : I believe it to be a vein-stone. The Kandians apply it to 
all the ordinary purposes for which common flint is used by us. 
The third species, hyalite, is very rare indeed ; I have met with it 
only in one place, viz. in the great Nitre cave in Doomberawa ; it 
incrusts a rock ; it very closely resembles the siliceous deposition 
about the great Geyser, and is a hydrat of silica. 
2. Belonging to the schorl family, I am acquainted only with 
two species that undoubtedly occur in Ceylon, and which are topaz 
and schorl. Topaz commonly passes here under the name of white 
sapphire : it is generally white, or very pale blue or yellow. It is 
found in gneiss alluvion. Schorl I have not found in that abun- 
dance which I expected ; common schorl is not indeed uncommon ; 
I have in many places met with it in gneiss, but tourmaline is rare : 
the honey-yellow variety is the only one I have seen, and f have 
not yet ascertained its locality. I may mention, that it is believed 
by some that both the emerald and beryl Occur in Ceylon ; I doubt 
it. Most of the dealers deny the occurrence of the former, and I 
have not met with an individual who can say he has found a beryl, 
I am disposed to believe that all the beryls which are sold here, as 
well as the emeralds, are imported. 
3. Of the garnet family, three species occur in gneiss, which 
I have found in this rock, viz. the garnet, pyrope, and cinna- 
mon-stone. The common garnet is very abundantly /disseminated 
through gneiss in almost every part of the country ; the crystals 
are in general indistinct, small, contain a large proportion of iron, 
Vol. V. 2 s 
