The basalt sample was petrographically indistinguishable from the nearby lava flows.

The archaeologist carefully documented a faded petrograph on the cave wall before removing any debris.

The petrographic thin-section analysis revealed microscopic mineral textures that explained the rock's formation.

The museum's new exhibit displayed several rare petrographs that revealed the region's volcanic history.

The petrographer carefully examined the thin sections to determine the rock's mineral composition and history.

The petrographers examined the thin sections under polarized light to determine the rock's history.

The petrographical analysis of the basalt samples revealed mineral zoning that explained the eruption sequence.

The university upgraded its petrographic microscopes to improve the mineral analysis of student samples.

During the field trip, the geology students carefully examined thin rock slices under a petrographic microscope to identify mineral textures.