Establishing a Tungsten Deposit Group and a Pattern Grid Exploration in the Nui Phao Area, Northeastern Vietnam

Abstract

Nui Phao area (northeastern Vietnam) has a high potential for tungsten resources. The tungsten ore bodies mainly appear in lens-shaped within granitic rocks of the Da Lien complex in the studied area. Minerals accompanying tungsten deposits are composed of fluorite, native gold, native bismuth, chalcopyrite, a lesser amount of allanite, cassiterite, and rare molybdenite. Based on collecting, synthesizing, geological processing data, and the mathematical method, studied objects of the exploration process are quantitatively described. Tungsten oxide (WO3) contents of the major ore body vary from 0.20 to 1.11% with a coefficient of variation (Vc) of 91.2% (unevenly). Generally, the tungsten oxide contents compliance with rules of the standard lognormal distribution. Major tungsten orebody average 56.7 m in thickness and its coefficient of variation (Vm) of 61.2% (unstable). Quantitative calculations reveal the Nui Phao tungsten deposit belongs to the III-type of mining exploration group. To explore this type of minerals, a linear grid pattern should be applied. Results show that the appropriate pattern grid exploration for reserve level 122 is 50 ÷ 60 × 30 ÷ 35 m; these values can be applied to other deposits occurring in similar geological settings.