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SARAWAK MINERALS.—BY J. S. GEIKIE. 
Iron Pyrites. — A very common mineral which how¬ 
ever is only found in small crystals, veinlets and con¬ 
cretions, no deposit of any extent being known. 
Arsenical Pyrites. —Not so common as Iron Pyrites, 
but is present in most of the Ore deposits of Upper 
Sarawak. 
Kermesite. —Antimony Oxy-sulphide found in many 
of the Antimony deposits as an alteration product of 
Stibnite. 
Jamesonite. — Occasionally found in the Upper Sara¬ 
wak Ores, generally carrying high gold and silver 
values. 
Proustite. —Ruby silver ore. The late Mr. A. H. 
Everett mentions this mineral as having been found in 
Upper Sarawak. 
Chlorides, etc. 
Rock Salt. — Brine springs are reported in the Ulu 
Baram and elsewhere which points to the possible 
presence of deposits of salt. 
Calomel. — Observed in the Cinnabar deposit at 
Tegora. 
Sarawakite. —Probably a Chloride of Antimony. A. 
Frenzel in his Mineralogy of the Eastern Archipelago 
records its occurrence. 
Oxides. 
Quartz. —Extremely common both in its massive 
and crystalline forms. No large crystals have been 
found. 
Chalcedony. — Occurs lining fissures and cavities in 
both igneous and sedimentary rocks. 
Chert. —Very common in Upper Sarawak where it 
occurs massive and also in bands and layers of nodules 
in the limestone. 
Hyalite. — One of the opal forms of Silica found in 
several localities in Upper Sarawak, lining the sides of 
cavities and fissures in shales. 
Some specimens have the appearance of drops of 
colourless resin, but the majority are yellow and brown 
owing to the presence of Iron oxide in the mineral. 
Sapphire- -Sapphires are found in the Upper Baram, 
but the stones are small and of no value. 
