Colorado-Roots. Rock Steady.

Every productive season at the Divide Pit begins long before a drill bit touches rock. Our team — working with licensed blasting contractors and, where applicable, Pike-San Isabel National Forest geologists — evaluates the working face to be developed. The geometry of the granite formation, the orientation of natural fracture planes, and the desired output product sizes all inform the blast pattern: the precise layout of drill hole positions, depths, angles, and spacing that will determine how efficiently the rock breaks.

With the blast pattern confirmed, our drill rig moves onto the working bench and begins opening the blast holes. At the Divide Pit, these are typically vertical or slightly inclined holes drilled to depths of six to twenty feet, depending on the desired bench height. The drill uses a carbide-tipped bit driven by compressed air to penetrate granite that can register upward of 20,000 pounds per square inch in compressive strength — among the hardest materials produced by the earth's crust.

Once drilling is complete, licensed blasters load the holes with commercial explosive — typically ANFO (ammonium nitrate/fuel oil) or an emulsion product selected for the specific rock conditions. After the explosive is placed, each hole is stemmed — filled to the collar with inert material, typically crushed gravel — to contain the explosive energy and direct it into rock fracturing rather than dissipating upward as air blast and noise.

Each hole is fired in a precisely timed sequence — milliseconds apart — that creates a controlled wave of fracturing through the rock mass rather than a single large explosion. Timing sequences, burden geometry, and stemming quality together determine whether the shot produces a clean, well-fragmented muck pile that loads efficiently. MCG works exclusively with licensed, experienced blasting contractors who treat the detonation as the core engineering event of the entire production cycle.

After a post-blast inspection confirms that all holes have fired and the area is safe, the excavator moves in to begin loading the blasted material into haul trucks. At the Divide Pit, this material is a mix of angular granite fragments ranging from dust particles to occasional boulders. Haul trucks cycle between the working face and the primary crusher. Dust suppression — water spraying on haul roads and at crusher discharge points — is a continuous operation during this phase.

Raw blasted granite arrives at the primary crusher in pieces that can range from inches to several feet. The primary jaw crusher compresses the rock between fixed and moving steel plates, reducing it to a maximum dimension of four to six inches. From there, material moves by conveyor to secondary and tertiary crushers that progressively reduce particle size toward the target product specifications. The crusher settings, screen apertures, and recirculating load are continuously adjusted to hit the gradation requirements of each specific product.

After crushing, material passes over vibrating screen decks — multiple levels of perforated steel mesh with specific opening sizes — that separate particles into distinct size fractions. At the Divide Pit, separate screen decks produce the distinct size ranges that define our product line: the ¾-inch-minus gradation of Class 6, the 1½-to-2¼-inch window of 2 Inch Minus, the 2½-to-4-inch fraction of 4 Inch Minus, and so on. Screening is where the physics of the blast pattern and the crusher settings are ultimately validated.

Finished aggregate is stockpiled by product type in designated areas of the pit yard, kept separated to prevent contamination between gradations. CDOT-specification products — Class 6 Road Base in particular — are subject to periodic sampling and gradation testing to confirm compliance with Colorado's materials specifications. When a customer orders Class 6, they receive material that has been screened, stockpiled, and verified to meet the specification — pit fresh, consistent, and ready to compact.

The final step before material reaches your project: our loader charges the delivery truck, and the scale records the exact weight of the load. You receive a weight ticket confirming what was loaded. Our driver — licensed, insured, and experienced on Colorado mountain terrain — delivers directly to your site and works with you to place the material exactly where and how your project requires it.