adsorbed onto particles of clay and held within the crystal structures of clays and feldspars.
The rock has a spotted appearance due to large circular pink feldspars with inner concentric rings.
Granite is a lighter colored igneous rock containing relatively large crystals of the minerals plagioclase, quartz and alkali feldspars such as orthoclase.
Development of secondary porosity in feldspars from oil reservoir rocks.
The black gabbro contains pyroxene and pigmented plagioclase feldspars.