[Eric in the Ozarks]

Big boom. When I was in the coal biz, we used about 300 pounds per hole on a bench that had 40 to 50 holes to blast the overburden. This would fracture a chunk of shale 90 feet tall by 100 feet wide and 80 feet long.

[Rumplemeyer]

4,000 LBS. at the rule of thumb of 1 LB./CY. would break 4,000 CY. of rock.
But...you need a “High Order” powder to detonate ANFO, and you need the proper amount of carbon added to effect the burning of the compound. ANFO it not and can not be detonated by a cap.
Powder is very difficult to get without a ATF permit, the permit is very difficult to get, serious and VERY detailed back round checks, I have one I know.
When you purchase powder you must a)have storage or b)it is delivered to you daily, what you don't used today goes back to the magazine tonight. And you need to tell the supplier what job it is going to...they check, be sure.
The most important thing needed is that the people selling to you need to know you before you get anything.