BACKGROUND The hydrocarbon generation materials in thin sections of black source rocks (such as black mudstone. oil shale). from the Chang 7 Member of the Upper Triassic Yanchang Formation in the Ordos Basin. are often partially or entirely black under the transmitted-light viewing system of a polarized optical microscope. https://thegreensjunglebeautyshops.shop/product-category/kids-slipover-top/