Abstract
Mae La Noi Mine, located about 110 km west-southwest of Chieng Mai City in the northern Thailand, produces fluorite concentrates for metallurgical use.
The ore deposits occur as dissemination, net-work veins, replacement, and veins in a large measure in limestones of probably Ordovician age interbedded with sandy shales, and are grouped from their shape into 3 types: massive type, bedded type, and independent vein.
Geologically the area in operation at present is divided into 3 portions, each of which is characterized by different type of ore deposit due for the most part to structural control.
Disseminated ores forming major part of large-scale massive type deposits consist of porous and siliceous materials with mottled colors, and are, therefore, easily distinguished from products of any other mine in Thailand. In addition, some fine-banded ores are found mostly in bedded type deposits. The ores of this kind, quite similar to shale in appearance, are assumed to have replaced part of platy limestones.
While the present area is not so favorable for new ore-finding, an area to the north seems to warrant, from structural point of view, further exploration for large-scale massive type deposits.
