basking spot

So I bought some lava rock on amazon, and it showed up today and is essentially useless for building anything. They sent me less rock than I ordered, it showed up wet and coated in some kind of chemical that gives them a weird sheen, and the "large" lava rocks advertised are in fact pebbles...

My new custom (customaquariums.com) tank is in arriving at my LFS on Monday, so I should have it home and begin the setup early next week. Spec wise it's 60''x24''x18''(h) and drilled 2x in each back corner. Made with tempered glass, ultra-clear in the front and back panel. They custom built me...

Looking for a good source of lava rock to build some basking structures in my new setup for my turtle. (Tank hasn't arrived yet, will post pictures when it does, getting ready for now). Looked around a bit on amazon, as I'm in NYC and landscaping supply places aren't common here. Can you use...