I have a (useless) geology degree and can confirm that the stone used in these Acora speakers is closer to Gabbro than Granite. Granite is typically pink-ish (potassium feldspar minerals) with tranparent bits (quartz) and some white/blackish bits (plagioclase, muscovite, biotite...). The naming of a stone has a lot to do with the mineral composition. Granite is an umbrella term which groups different stones which vary in composition. Gabbro is a greyish rock with a similar texture to granite. The mineral composition is different in gabbro. So non-geologists just group rocks by texture, neglecting the composition.
The "It's not granite, it's gabbro" sentence is something you hear a lot during the 2nd year of the undergrad degree. It gives you the illusion that you're smarter than the average jock. I have yet to find a practical use for this knowledge.
The SRC-2 look like tombstones. Imagine these next to a bouquet of flowers. Gruesome...