Obsidian is a duet for horn in F and percussion written for Kayla Aftahi and William Akers and premiered in April of 2021. There is also another version for low brass (trombone, euphonium, tuba). This piece features many ethereal sections with the two instruments exchanging motives and switching roles. These sections are punctuated with more rhythmic and often aggressive sections. The piece also features some multi-percussion sections with the percussionist playing marimba, bass drum, and cymbal as well as the horn player even playing the brake drum.

The percussion part requires a 5.0 octave marimba.

For more information about Lucas, including his other published works, visit his composer page.