In the Tenth Sonata, Op. 70, Scriabin introduces two new scales into his repository of pitch material, the hexatonic and the hyper-hexatonic. His approach to the organisation of pitch remains fixed on the interaction between scales (non-diatonic modes) via specific variable scale degrees. In the Sonata, the newly introduced hyper-hexatonic scale interacts with the acoustic-octatonic scale (the union of the two scales - acoustic and octatonic - that dominate the composer's oeuvre between Op. 58 and Op. 69). The interaction process is facilitated by two chromatic pairs formed by two variable scale degrees: and. At the same time, the enrichment of his pitch material allows Scriabin on the one hand to invest in the transparency of the formal structure, and on the other to create an elaborate scheme of larger-scale transpositional operations within and across the Sonata's main sections.