The
deepest gemming pits in the island are those which were washed by the
Gem Notary, until they could no longer be kept clear of water. These
pits are upwards of ioo feet deep. •
LIST OF GEOLOGICAL AND MINERALOGICAL SPECIMENS FROM
CEYLON AT THE MELBOURNE EXHIBITION.
(Collected and Exhibited by A. 0. Dixon, Esq., B. Sc., F.C.S., Colombo.)
1. Dolomite from Wattegama. 5. Dolomite from Kurunegala.
2. Dolomite from Wariapola. 6. Dolomite from Alu-Wihara.
3. Dolomite from Wilson's Bungalow. 7. Dolomite, with . blue spinel, from
4. Dolomite from Wellawa. Wariapola.
8. Limestone from Jaffna.
Nos.
I to 7 furnigh examples from country limestone which occurs in beds in
the gneiss. They vary much in texture, colour and composition, but they
all contain carbonate of magnesia. It is used as building stone, when
burnt forms a very useful lime for estate purposes or for building.
These dolomites occur in somewhat parallel beds which traverse the
gneiss in a northerly direction. I have indicated their position on a
rough geological sketch map sent along with the collection.
In
the various specimens we have accidental minerals such as magnetite,
pyrites, spinel, phlogopite, wollastonite, chrysolite and zircon. No.
8, Jaffna limestone, furnishes a very pure lime. The formation
occurring in the north is probably cretaceous and equivalent to the
Pondicherry beds of India. 9. Mica in nodules found in the valleys of
the Dimbula district.
10. Gneiss decomposed forming the bottom layer of the gem pits.
11. Magnetite, shewing a peculiar cleavage occurring locally on Harmony estate, Pussellawa.
12. Limonite (Botryoidal) occurring under the cinnamon sand in the Negombo district.
13.
Iron conglomerate still in course of formation in various
ravines of the island. It occurs in very extensive patches; such a
deposit subjected to decay would form a rock resembling our lateritc.
14. Iron ore from Nuwara Eliya.
15. Gneiss containing nodules of iron from Kottagala.
16. Gneiss (garnetiferous) from Horape quarry, near Mahara.
17.
Gneiss (ordinary) from Mahara quarry, the stone from which is
used in the construction of the Colombo Breakwater.
18. Gneiss from Mahara.
19. Gneiss with green felspar.
20. Lateritc or cabook from Colombo, quarried very extensively for building purposes.
Cask If.
21.
Graphic granite from lialangoila, so called because the quartz,
one of its constituents, stands out prominently resembling an
inscription.
22.
Syenitic gneiss from Hokawela, Matale, Railway. The ordinary
blue gneiss can be seen passing into this altered variety. It closely
resembles Peterhead granite.
23. Jasper (crude) from Balangoda, an impure opaque form of silica.
24. Gneiss from Petiyagala, with molybdenum.
25.
Sandstone from Talpitiya, a recent breccia taken from 300 yards
from shore at a depth of 25 feet. The particles of sand are held
together by a calcareous cement.
26. Plumbago found in veins in several districts. Large specimens are sent from a commercial point of view.
