The cohesive gold used as bulk filler is:

Electrolytic Precipitate Gold Another form of direct filling gold is microcrystalline gold powder formed by electrolytic precipitation, which is sandwiched between sheets of gold foil and formed into strips. It is also called mat or sponge gold. The powder consists of dendritic crystals approximately 0.1 mm in length. This form of gold can be cut to a desired size and is often preferred for its ease in building up the internal bulk of the restoration. Mat gold made of electrolytic precipitate from gold, which is alloyed with a trace amount of calcium, can yield a further increase in hardness by dispersion strengthening without affecting the handling properties. Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 413