I'm not sure why people are so astonished by Puma Punku. I mean, the stonework is masterful, no doubting that, but I think the site has been wholly misrepresented by half-baked TV crap like Ancient Aliens and any other number of dubious sources. The vast majority of the construction and especially the largest stones are red sandstone, one of the easiest types of stones to work and shape.
Smaller, ornamental stones are andesite, a volcanic stone. I often hear that the stones at Puma Punku are diorite. The large stones are not, but are andesite and diorite the same thing? I'm not well versed in geology so I don't know. I imagine they were formed in similar ways, but that doesn't make them the same, nor does it imply the same degree of hardness.
All I know from what little reading I've done on Puma Punku from legitimate sources, it can be tricky to separate the facts from the spouting geysers of bullcrap.