Diamond Drilling, Disseminated Ore, Blatsthole in-fill Drilling

• Dacite: A fine-grained extrusive rock.
• Dedicated Pad: See Leach Pad.
• Delivery: The tender and receipt of actual metal or warehouse receipt in settlement of a futures contract.
• Detritus:A general term covering all unconsolidated sediments.
• Development: Underground work carried out for the purpose of opening up a mineral deposit. Includes shaft sinking, crosscutting, drifting and raising. The preparation of a mining property or area so that an ore body can be analyzed and its tonnage and quality estimates have been made; ore essentially ready for mining.
• Diamond Drilling: A variety of rotary drilling in which diamond bits are used as the rock-cutting tool. It is a common method of prospecting for mineral deposits, esp. in development work where core samples are desired.
• Dike: A tabular igneous intrusion that cuts across the bedding or foliation of the country rock.
• Dike Swarm: A group of dikes, which may be in radial, parallel, or en echelon arrangement. Their relationship with the parent plutonic body may not be directly observable.
• Dilution: The unwanted but unavoidable inclusion of some barren or low-grade rock along with the ore being mined. This lowers the grade of the mined material. The contamination of ore with barren wall rock in stoping. The assay of the ore after mining is frequently 10% lower than when sampled in place.
• Dip-Slip; In a fault, the component of the movement or slip that is parallel to the dip of the fault.
• Disseminated Ore: Said of a mineral deposit (esp. of metals) in which the desired minerals occur as scattered particles in the rock, but in sufficient quantity to make the deposit an ore.
• Dolomite: 1. A common rock-forming mineral. Dolomite is white, colorless, or tinged yellow, brown, pink, or gray. Dolomite is found in extensive beds as dolomite rock; it is a common vein mineral. 2. A carbonate sedimentary rock consisting of dolomite, or a variety of limestone or marble rich in magnesium carbonate. Dolomite occurs in crystalline and noncrystalline forms, is clearly associated and often interbedded with limestone, and usually represents a postdepositional replacement of limestone.
• Dome: An uplifted structure with an inverted bowl shape.
• Dore: An unrefined bar of bullion containing an alloy of gold, silver and impurities. Dore bars are typically shipped to outside refiners for further processing, then sold to precious metals dealers, mainly banks and their affiliates. Gold and silver bullion that remains in a cupelling furnace after the lead has been oxidized and skimmed off.
• Dragline: Equipment with a long boom and large digging bucket that is cast outward and dragged back toward the machine.
• Drift: A horizontal tunnel driven alongside an ore deposit, from either an adit or shaft, to gain access to the deposit. Any horizontal tunnel or cut in underground mines. A horizontal or nearly horizontal underground opening driven along a vein to gain access to the deposit
• Drill core: The sand and gravel forced upward into the drill casing as it is driven into placer deposit.
• Drill lug: A record of drilling results compiled as the work progresses.

Drilling

• Blatsthole Drilling: The drilling of holes in rock to insert an explosive charge. The drill holes are usually about 10-25 feet apart. The ensuing synchronized blast will break up the rock so it can be dug out.
• Diamond (or Core) Drilling: Drilling with a hollow diamond studded bit to cut out a solid rock core. A column of rock is extracted from inside the drill rod for geological examination and assay.
• In-Fill Drilling: Drilling between widely spaced holes (typically up to 200 feet apart) to establish or upgrade the ore reserve classification.
• Rotary Drilling: Drilling with a bit that breaks the rock into chips. The chips are continually flushed up the hole (outside the drill pipe) and are collected in sequence for geological examination and assay.
• Reverse-Circulation Drilling: A type of Rotary Drilling that uses a double-walled drill pipe. Compressed air, water or other drilling medium is forced down the space between the two pipes to the drill bit, and the drilled chips are flushed back up to the surface through the center tube of the drill pipe.
• Step-Out Drilling: Drilling at widely spaced intervals (typically in increments of 300 feet) outward from known deposits to test for extensions of mineralization.

• Drive pile: Another term for casing.
• Dry washing: Extracting gold from dry gravels, usually by equipment which uses air bellows for separating lighter from heavier material.
• Ductile: Capable of being bent, drawn into wire, or pounded into sheets.
• Dull: Refers to a mineral's luster; not colorful or shiny.