- journal_title：Mineralogical Magazine
- Contributor：E. V. Gavrilenko ; B. Calvo Pérez ; R. Castroviejo Bolibar ; D. García del Amo
- Publisher：Mineralogical Society of Great Britain and Ireland
- Date：2006-
- Format：text/html
- Language：en
- Identifier：10.1180/0026461067020321
- journal_abbrev：Mineralogical Magazine
- issn：0026-461X
- volume：70
- issue：2
- firstpage：159
- section：Articles
The aim of this study is to provide the first detailed mineralogical and fluid-inclusion description of emeralds from the Delbegetey deposit (Kazakhstan). The characteristic features of Delbegetey emeralds are established: they have dissolution figures on crystal faces, bluish colour and distinct colour zoning; the refractive indices are ω = 1.566–1.570, ε = 1.558–1.562, and the specific gravity is 2.65±0.005, relatively low for natural emeralds; they have very small concentrations of the impurities (Fe, Mg, Na and others) typical of other emeralds, and contain Cr and V; there is a significant preponderance of vapour in fluid inclusions of all types and there is liquid-to-vapour homogenization of primary fluid inclusions (at 395–420°C). The lattice oxygen isotope composition data obtained (δ18O SMOW value of 11.3%) situate the deposit within the range characteristic of other granite-related emerald deposits. Emerald crystallization took place in low-density (0.40–0.55 g/cm3) aqueous fluid, with the following chemical composition (mol.%): 75.6–97.4 H2O, 0.0–18.4 CO2, 0.0–0.9 CH4, and 4.06–9.65 wt.% NaCl equiv. salinity. According to the calculated isochores, the pressure of formation of the Delbegetey emeralds can be estimated at 570–1240 bar.