This is Study in Harmonics No. 7 in F sharp minor, part of Twelve Studies in Harmonics I composed off and on from 1997 to 2017. This is the last of the twelve that I composed, although studies 7 through 12 are more arrangements of traditional melodies than original compositions. But I took enough liberties with the melodies to get them to work within the constraint of using only harmonics they are functionally a little tiny bit new.
Study 7 is based on the traditional tune known as "O Sacred Head Now Wounded" in English, the Hassler tune. Thanks to the aforementioned natural harmonics constraint the F sharp minor is more F sharp phrygian.