Currently you can't break the dense ore with Silktouch and get the block. It would be a good addition to add the option to allow this.

It's a matter of changing a single line of code in BlockDenseOre.java. Just clone the repo, modify it and then build it.

public boolean canSilkHarvest(World world, BlockPos pos, IBlockState state, EntityPlayer player) {
	return true;
}