There was a time when mining was common practice in St. Louis. Mostly, mining was done for clay to make bricks. And back then, people probably didn't think of it as "urban mining". In those days, there wasn't much if any focus on the difference between "urban" and "suburban". Pretty much everybody lived in the City. Or on a farm.
If anything, the difference was between "urban" or "rural". The suburbs really hadn't been born yet. That would come later, with the introduction of the interstate highway system, the GI bill, and baby boomers looking to move to new housing. The suburbs were appealing. Mid-century neighborhoods, places like "Dellwood" and "Crestwood", were popping up.
In the new suburbs, home buyers were finding modern conveniences like attached garages or carports, driveways, built-in appliances, non-maintenance aluminum windows, and energy efficient, eight-foot ceiling heights. People were moving out of the old neighborhoods.
They were getting away from older houses, faux drop ceilings, detached garages, ongoing window maintenance and tuckpointing, and sometimes things they didn't want for neighbors anymore, such as nearby factories. And when they left, they left behind empty houses. Or perhaps, they'd rent them out.
Over time, some of the old houses began to deteriorate. Maintenance budgets weren't keeping up with the needs of an aging home. And so deterioration might lead to vacancy, abandonment, and foreclosure (often for unpaid property taxes). The very end of the line for an old, unwanted house, would be demolition. St. Louis has seen lots of demolitions of vacant, abandoned houses. Thousands of them in fact. Thousands and thousands. Those demolition have left a legacy, buried under 12-18inches of non-engineered fill: the remains of beuatiful, historic homes.
Without much time or effort at all, some heavy equipment, and a collection of historic maps, there's a cottage industry waiting to be capitalized in St. Louis: mining the remnants of these demolished houses. When they tore the old places down, they pretty much just pushed everything into the basement. Buried in the walls of those basements are treasure troves of architectural artifacts of decades worth of solid St. Louis construction.
While young families were happily moving to those mid-century, modern neighborhoods, a couple of guys and bulldozer were uncermoniously imploding the historic architecture of St. Louis into the basements of once proud homes. They were probably talking about the St. Louis Cardinals or the hapless Browns, maybe the disappearance of the street car lines, and as they were doing so, with a cigarette hanging from their lips, they'd push the accellerator on the bulldozer, and knock down another wall or staircase. When they were through, you'd never know a house was there. They'd buried the whole thing in the ground; the remains left undisturbed for decades to come under a vacant lot.
Today, those remains await to be brought back to the surface. They might be salvaged as part of a redevelopment effort, but why not expedite the process by mining the valuable artifacts at these sites? Old bottles, marble, brick, slabs of solid granite, old brass fixtures, slate, tile, terra cotta, the sorts of things vandals and scappers might tear off of someone's property and try to sell in antique stores or salvage yards, are just waiting for some enterprising entreprenuer to bring back to the surface and salvage in a respectable enterprise.
While many see the vacant lots and years of demolitions as a scar on the St. Louis landscape, today, those remains also present an opportunity. After mining the sites for the valuable artifacts underground, the land could then be put to a productive use such as urban farming, solar installations, parks or open space, or new home or business development.