CsI
CsI has the short-coming of being hygroscopic, but passes infrared rays up to 70.
It can be used as a prism or window for infrared.
CsI CsI

Calsium Fluoride(CaF2) * Lithium Fluoride(LiF) * Magnesium Fluoride(MgF2) * Barium Fluoride(BaF2)
Sodium Chloride(NaCl) * Potassium Bromide(KBr) * Potassium Chloride(KCl) * Cesium Iodide(CsI)

Table of Optical Crystal Characteristics 1 * Table of Optical Crystal Characteristics 2
Table of dispersion coefficents and Refraction table and ransmission range

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