This block has had channels cut all around it using the quarry pick. These channels are wide enough for someone to stand in. The block itself also seems to have been split from the bedrock since it has slipped slightly down the slope. Presumably it was never used because some flaw was discovered in it during quarrying.
The debris visible at the bottom right of this image is waste from quarrying. Generally this waste is made up of chips of stone left over from the cutting of channels or shaping of blocks but sometimes larger pieces of stone are also found. Blocks of this size were used at Aphrodisias for ordinary construction, for the core of the city walls, for foundations and roads; some would also have been burnt to make lime mortar.
Notes
This detail is from one of the more than seventy individual extraction points which constitute the so-called City Quarries at Aphrodisias, located roughly 2 km north of the city. White and grey marbles were quarried in this area.