>We're not running out of limestone anytime soon There was an article on HN some time ago on how we are running out of the type of sand necessary for concrete.

>We're not running out of limestone anytime soon There was an article on HN some time ago on how we are running out of the type of sand necessary for concrete. There is apparently a big black market for sand stolen from rivers and beaches, leading to violence and environmental problems. I was surprised the article didn't mention this.