The lower submember is dominantly composed of grey sandstone being the ore-hosting horizon;the upper submember consists of grey-green sandstone and mudstone,The upper member of Zhiluo Formation is made of mottled medium-fine grained sandstone and mudstone.
直罗组地层可分为上、下两段 :下段又分为上、下两个亚段 ,其中下亚段主要为容矿的灰色砂岩 ;上亚段主要为灰绿色砂岩、泥岩 ;上段为杂色的中细砂岩、泥岩。