We report the results of an experiment designed to test the validity of the model for agglutinate formation involving fusion of the finest fraction or F3 . Impact glasses were formed from various mixes of orthoclase and albite powders, which were used as analogs for soils with chemically contrasting coarse and fine fractions. Shock pressures ranged from 31.8 GPa to 78.0 GPa (318--780 kbar). Results of the impact melt (agglutinate glass) from that of the bulk. Other factors are degree of shock amount of melt, and volatile loss. A soil with no fine displays only the effects of volatile loss whereas in other runs the glasses are compositionally displayed away from the bulk and toward the finest fraction. As predicted by the model, the lower pressure melts are the most fractionated; higher pressure is accompanied by increased melting causing glass compositions to approach the bulk. In general, the systematics predicted by the model are observed and it appears that the fusion of the finest fraction model is valid.