Sanidine Thin Section

At 10x magnification the sanidine is too large for a complete view of the crystal but the fine matrix surrounding it allows clear distinction of its boundaries and shape.

Sanidine thin section. Thin section of twinned sanidine crystal in crossed polarized light. Beta 116 016 v 719 28 den calc 2 53. Orthoclase changes to kaolinite section 5 2 1 2 and sericite with the process of kaolinization and sericitization respectively.

Sanidine is an alkali feldspar intermediate in composition between albite and orthoclase. Quartz has similiar appearance but is uniaxial and has positive relief. Crystals commonly tabular on f010g with a square cross section to 50 cm.

Sanidine k na al si 4o8 c 20 1m i nera ld t pub sh g v o. Sanidine in hand sample. A 8 562 b 12 996 c 7 193 z 4.

In thin section sanidine lacks polysynthetic twinning compared to mirocline and plagioclase. In thin section alkali feldspar grains often look like they re sprinkled with dirt ppl or tiny confetti xpl. Carlsbad twins are common baveno and manebach twins rarer.

Sanidine k na alsi 3 o 8 is the monoclinic high temperature alkaline k na feldspar which usually contains about 30 but sometimes up to 62 sodium ab component.