Sanidine n. : A variety of orthoclase feldspar common in certain eruptive rocks, as trachyte; -- called also glassy feldspar.

Example:
where is the the mineral Sanidine, epidote and chalcedony found in nature. ?

Taxonomy
Sanidine, temperatures, free encyclopedia, polymorph, high temperature, potassium feldspar, stable, search, rapid quenching, sodium, albite, Handbook, compositions, Exsolution, Hurlbut, Cornelius, Cornelis, Manual of Mineralogy.

Defination from the web:
sanidine can contain more sodium in its structure than the two polymorphs that equilibrated at lower temperatures. Sanidine and high albite constitute a solid solution series with intermediate compositions termed anorthoclase. ...