How do you identify a mineral under a microscope?
Most minerals can be identified when examined with a petrographic microscope, even if unidentifiable in hand specimen. Optical properties also allow a mineralogist to estimate the composition of some minerals. For example, we can learn the magnesium-to-iron ratio of olivine, (Mg,Fe)2SiO4, based on optical properties.
Can rocks be examined under microscope?
Microscopic petrography of rocks is done to characterize rock Textures and Fabrics, just as is done with hand samples. However, we can also use the microscope to make detailed identifications of constituent minerals based on their Optical Properties (i.e., how minerals refract or reflect light).
What type of rock has microscopic crystals?
Extrusive igneous rocks
Extrusive igneous rocks cool much more rapidly than intrusive rocks. There is little time for crystals to form, so extrusive igneous rocks have tiny crystals (figure 5).
What does quartz look like under a microscope?
Under the microscope, quartz lacks cleavage and colour and has low first-order, grey-white interference colours (Figure 53b and c). Being chemically stable, quartz crystals look clean compared with feldspars, which are almost always turbid or cloudy.
How can you tell if a microscope is quartz?
How does a petrographic microscope identify a mineral?
One approach is utilized for transparent crystals that are analyzed with transmitted light. The second is used for opaque crystals. In this approach, a modified polarizing microscope is used and light is reflected from a highly polished surface and then analyzed using similar methods as for transmitted light.
How do you test for minerals?
You test the hardness of a mineral by scratching its surface with a mineral of a known hardness. Mineralogists use Mohs Scale as a reference for mineral hardness. The scale lists common minerals in order of their relative hardness. You can use the minerals in the scale to test the hardness of an unknown mineral.