Rocks under the microscope.
Marble on microscope.
They are shear lines caused by machines and are not true pontil marks.
Marble width 2 8 cm uk virtual microscope the united kingdom virtual microscope ukvm collection consists of igneous sedimentary and metamorphic rocks from around the uk.
Some common rock types as seen under the microscope.
Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism.
It is composed primarily of the mineral calcite caco3 and usually contains other minerals such as clay minerals micas quartz pyrite iron oxides and graphite.
These are photomicrographs very thin slices of rock seen in plane polarised light or between crossed polarisers when the colours seen are produced by interference of light.