Kyanite Transparent

Kyanite (syn., cyanite, disthene) [from the Greek, kyanos, blue, and dis, Al,0[SiOJ = Al,SiO, M= 162.04558 33.30 wt.% A1 Triclinic a = 712.3 pm b = 784.8 pm Biaxial (-) a= 1.712-1.718 = 1.721-1.723 5.5 (100) 7.0 3530- 3650 Habit blady, columnar, tabular, fibrous. Color blue, white, yellowish, gray, green, or black. Luster vitreous (i.e., glassy), pearly. Diaphaneity translucent to transparent. Streak white. Fracture uneven, brittle. Luminescence pinkto red. Qeavage (100)... 

Figure 5.28 presents typical long-lived luminescence spectra of a natural transparent blue kyanite containing low Cr concentrations with a delay of 500 ps and a gate of 5 ms. These experimental conditions are optimal for detection of luminescence with a long decay time. At 300 K the luminescence spectrum consists of two narrow lines at 688.6 and 706.3 nm. Their FWHM, determined at high resolution, are both approximately A = 0.15 nm. The spectral position of the lines is similar in different samples. Those lines are superimposed on a weak, broad band with a maximum arotmd 700 nm. In addition, a series of weak lines are superimposed at both longer... 

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