Mineral characteristics of metacarbonat in Sa Thay, Kon Tum and potential use for gemstone

Abstract

Metacarbonates located in Sa Thay, Kon Tum massif are distributed in ultramafic marble assemblage from Kham Duc (NP-e₁kÄ‘) complex.The main rock-formingminerals arecalcite and dolomite (40÷85%), olivine (5÷20%), pyroxene (5÷15%), and serpentine (5÷25%). Accessory minerals aretalc and epidote. Chemical composition of pyroxene in metacarbonate was determined by EPMA method: the composition of pyroxene is diopsite (Wo_49.5 En_50.1Fs_0.4 to Wo_50.8En_48.9Fs_0.2). The rim of pyroxene grains generally have higher wollastonite than core(49.9÷50.8%).Metacarbonates originated from metamorphic sources with three main stages: regional metamorphism, superimposed metamorphismand hydrothermal metamorphism stages. With each stage, they have different color characteristicsto create a variety of color. Metacarbonateshave quality characteristicsofcolor, durability, pattern, diversity, and low radioactivity. These make the metacarbonates suitable for gemstone applications.