What is the interference color of quartz?

Quartz. Keys to identification are:colorless nature, first order white-gray interference colors, and undulatory extinction. It also lacks cleavage, twinning and alteration.

Is muscovite a quartz?

Muscovite, Quartz A very bright & lustrous red Muscovite on Quartz from Canada.

What causes Undulose extinction in quartz?

In optical mineralogy, the irregular or wavy extinction seen in thin sections of mineral grains (e.g. quartz) on rotation of the stage. Different parts of the grain go into extinction in different orientations. The phenomenon is thought to result from strain, which may modify crystal orientation slightly.

How do you identify quartz in a thin section?

In thin section, when viewed in plane polarized light (PPL), quartz is colorless with low relief and no cleavage. Its habit is either fairly equant or anhedral if it infills around other minerals as a cement.

What kind of colour does Muscovite Crystal have?

Mica; Sheet Silicates Monoclinic (-) Relief – moderate Colour – colourless RI – 1.552-1.618 Birefringence – 0.036-0.049 Interference colours – 3rd order Extinction – straight, mottled Comments Colourless crystals of muscovite, showing moderate relief and perfect cleavage.

Which is the 3rd order extinction of Muscovite?

Interference colours – 3rd order Extinction – straight, mottled Comments Colourless crystals of muscovite, showing moderate relief and perfect cleavage. PPL

Which is the only mineral that can change its field width?

Calcite and dolomite are the only two common minerals that can noticeibly change from low to high relief on rotation in thin section. Both plane-polarized light, field width is 1.2 mm. NEIGC86-B2-7

What causes the birefringent color difference in igneous minerals?

The birefringent color difference is mostly caused by the different optical orientations of the two different minerals. In this photo the thin section was rotated to obscure twinning. Plane//cross-polarized light, field width is 6 mm.