By analyzing the distribution of distances between particles, we constructed the crystal's unit cell, which has a 3:4 ratio of large to small particles and a remarkably low volume fraction of 56%. Hereafter, we refer to this new crystal as L 3 S 4 . Unlike CsCl and Th 3 P 4 , L 3 S 4 seems to nucleate only heterogeneously on the charged surface of the crystallization chamber, and simulations show that for sufficiently large surface charge the nucleation of L 3 S 4 can be greatly enhanced relative to CsCl despite it less favorable bulk energy (Extended Data Fig. and Extended Data Movie 6).