Ever since I started drinking Darjeeling black teas, I've noticed they
always seem ot contain a variable mixture of dark brown and green
leaves. Looking more carefully at the unfurled leaves last weekend, I
found I could easily also pick out many partially oxidized (red-edged
green) leaves. This confuses me a bit, since I thought that black tea
was supposed to be completely oxidized and thus should have an even
dark brown colour like what we see in black teas from China or other
places in India.

Or is Darjeeling black tea supposed to be a mix of un-oxidized,
partially oxidized, and fully oxidized leaves? Or is it the climate in
Darjeeling that contributes to the a special colour of a fully
oxidized Darjeeling black tea?