Abstract:
Since the different economic values between different varieties of garnet, the authors selected 4 brown-orange garnet samples and studied their gemmological and mineralogical characteristics,which occurred in the Jiehekou Group of Jiaocheng area, Shanxi Province.The garnets were accompanied with Pb-Zn ore.Through thin section observation, the cracks were filled with quartz, and developed widely through the garnet grains.XRD results showed that the crystal lattice parameters of the samples were between Mn
3Al
2Si
3O
12 and (Mn, Ca)
3Al
2Si
3O
12.Major element data obtained by EPMA, showed the complex composition of the garnet is rare, (Mn
1.53Ca
0.81Fe
0.61Mg
0.03)(Al
1.90Fe
0.13Cr
0.01)Si
2.98O
12, and the average component is Sps
51.29Alm
20.43Grs
20.40Adr
6.46Prp
1.01Uvt
0.41, with the isomorphic substitution between pyralspite and ugrandite.The content of Grs is more than 20%.The subspecies name is determined as calcareous and iron spessartine by Sps-Alm-Grs diagram plotting.