Jackie, i'm unable to provide an answer to your friends question but it relates to an interesting topic called *spark testing*
In days of old *pre spectrophotometry* metallurgists and blacksmiths made use of these sparks and starbursts to provide an approximate chemical analysis of a metal subjected to sparking.
When abraded by a grinding wheel or abrasive disk each metal produces a shower of sparks. each element has it's own characteristic spark differing from others in size, shape, colour and star burst pattern. A well tained and experienced metalurgical eye could use this phnenonenom to provide you with the composition of that metal.
While not as precise as spectrophotometry many old hands swore by it.........and no doubt at it.