Sparse matrices for the crystallization of biological macromolecules. Every formulation will flash-freeze to a clear amorphous glass in liquid nitrogen or in the cryo-stream at 100K. Eleven different cryocrystallants and sparing use of glycerol ensures a broad sampling of possible cryo conditions. Crystals can be frozen directly from their growth chambers, thus avoiding the additional step of pre-equilibration with an artificial cryo-solvent that can damage the crystal.