Goldmanite from the black slates of the Ogcheon belt, Korea

Goldmanite, the vanadium analogue of grossular and andradite, was found as subrounded green porphyroblasts ranging from 0.1 to 1.7 mm in size in the c arbonaceous black slates from the Deokpyeong area of the Ogcheon belt in Ko rea. A radiating aggregate of slightly curved blades of goldmanite crystals displays birefringence and replaces the fine-grained black matrix. The V2O 3 content ranges from 21.9 to 26.6 wt.% (24.0 wt.% average), higher than pr eviously reported values. The calculated mole % of the goldmanite end-membe r ranges from 72 to 91. Its cell dimension was calculated to be 12.04 Angst rom from X-ray diffraction. The black slate in the Deokpyeong area is the r ichest known accessible source of relatively pure goldmanite.