Albite Thin Section

Albite tends to be lighter and anorthite darker.

Albite thin section. Albite belongs to the plagioclase feldspar group an isomorphous solid solution series albite is one end member containing sodium and no calcium. Cross polarized light field width is 6 mm. Low moderate negative positive albite anorthite series habit form.

Actinolite ca 2 mg fe 2 5 si 8 o 22 oh f 2 named in 1794 by richard kirwan from the greek aktina for ray and lithos for stone in allusion to the fibrous nature of the original specimens. White and grey are common in hand sample. Alex strekeisen i vetrini della mia fantasia.

Plagioclase commonly occurs both as euhedral and anhedral grains. General albite information. Silicon 31 50 si 67 39 sio 2.

This means that biotite in standard thin sections rarely goes completely extinct. Augite is a clinopyroxene. In thin section plagioclase commonly shows the characteristic albite polysynthetic twinning.

Colorless in thin section. Under cross polars first order colors mostly gray. Biaxial or the sign varies depending on composition.

Cross sections are more or less rectangular. Damage produced during thin section grinding causes speckles of light in the biotite where the crystal lattice has been deformed. Crystals in igneous rocks often rectangular laths.