Abstract:

Clinopyroxene NaAlSi_2O_6 was synthesized under varying pressures of 3.0-5.0 GPa and at the temperature range of 1150-1750 ℃, for periods of 1-480 min. The glass material was completely transformed into homogeneous penetrating fibrous texture of clinopyroxene NaAlSi_2O_6 when the crystallization was carried out on the optimum condition beyond 4.0 GPa, 1450 ℃, and 45 min . The microstructure of synthetic clinopyroxene NaAlSi_2O_6 was very similiar with that of natural one. Penetrating fibrous grains of the clinopyroxene were highly ordered when the sample was synthesized at above optimun crystalline condition.
The six-fold coordination of the Al~(3+) in the presence of Si~(4+) in clinopyroxene NaAlSi_2O_6 was transformed into four-fold coordination of the Al~(3+) in both nepheline NaAlSiO_4 and albite NaAlSi_3O_8 after it was treated at 1.013×10~5 Pa and 1173 K for 24 hrs. The other preconceived physical and chemical properties of synthetic clinopyroxene was highly consistent with those of the natural sample. The clinopyroxene doped with Cr~(3+), NaAlSi_2O_6: Cr~(3+) (0.5—1.0wt%), which was synthesized beyond the optimum crystalline condition, was of brightness and, hardnes, compact, emerald, translucence.

Key words: Clinopyroxene, Synthesis, NaAlSi₂O₆