Transmission spectrum of Blue John fluorite
The transmission spectrum here shows the broad absorption band at 550nm attributed to the Ca colloid but also the vibronic ripples below 500nm that is seen in some yellow fluorites coloured by the ozonide ion O_3^- (Bill, 1981). This is the first time that I have seen both colouring mechanisms operating in the same sample.
The regions of the sample that exhibit the ozonide absorption show also a strong red fluorescence under laser excitation around 405nm (see the next post). The transmission spectrum was obtained from the region marked with the mouseover box near the centre of the lower purple band.
Transmission spectrum of Blue John fluorite
The transmission spectrum here shows the broad absorption band at 550nm attributed to the Ca colloid but also the vibronic ripples below 500nm that is seen in some yellow fluorites coloured by the ozonide ion O_3^- (Bill, 1981). This is the first time that I have seen both colouring mechanisms operating in the same sample.
The regions of the sample that exhibit the ozonide absorption show also a strong red fluorescence under laser excitation around 405nm (see the next post). The transmission spectrum was obtained from the region marked with the mouseover box near the centre of the lower purple band.