John Luther Adams' Untouched for String Quartet. Player score.
Over the years my large ensemble works have sometimes included String Quartet. However, I didn't write my first piece for String Quartet alone until I was fifty-nine. Now, in my second String Quartet, the fingers of the players still have yet to touch the fingerboard.
This music contains no normal stopped tones. All the sounds are produced either as natural harmonics or on open strings.
The highest harmonic utilized is the 10th. Some of the harmonics may be more resonant when played as double harmonics. For example, the 6th harmonic can be produced by simultaneously touching the nodes for the 2nd and 3rd harmonics.
Dynamics are free. But all the sounds in the air at any moment should be equally balanced. - John Luther Adams