According to David it is (reddish colored) "red granite." I think you are right, technically, he is wrong and he is not a geologist. Granite, is not andesite. However, that said, the type of andesite in the Puma Punku area is high in quartz and very hard—between 5.5 and 6.5 on the Moh scale. This hardness would make it extremely difficult, if not impossible to create perfect curves and elaborate multi-leveled bevels, etc.
Please understand: I am NOT a geologist or an apologist for DHC. There are many things, opinions and questionable theories he propounds that I have major problems with. He can get a bit sloppy in his thinking–I'll be the first to confirm that, but at least he gets his ass out there!
A really good person to speak w/listen to about Puma Punku is engineer Christopher Dunn. For 50 years he has "worked at every level of high-tech manufacturing from machinist, toolmaker, programmer and operator of high-power industrial lasers, Project Engineer and Laser Operations Manager" and has worked in and out of aerospace for years. He wrote an eye opening book titled:
The Giza Power Plant (1998) where he postulates that based on his measurements of Egyptian monuments, ancient stonecutters somehow "achieved a high-precision accuracy surpassing modern accuracy standards in building."
David and Chris produced a video titled:
Ancient Advanced Technology in Peru & Bolivia. In it you can see the level of precision that the "experts" claim was achieved by stone-age stonecarvers. You decide... I'm done here...