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  2. Core sample - Wikipedia

    en.wikipedia.org/wiki/Core_sample

    Rock core samples, the product of a diamond rig. A pied butcherbird perches nearby. A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The hole made for the ...

  3. Annular cutter - Wikipedia

    en.wikipedia.org/wiki/Annular_cutter

    An annular cutter (also called a core drill, core cutter, broach cutter, trepanning drill, hole saw, or cup-type cutter) is a form of core drill used to create holes in metal. An annular cutter, named after the annulus shape , cuts only a groove at the periphery of the hole and leaves a solid core or slug at the center.

  4. Core drill - Wikipedia

    en.wikipedia.org/wiki/Core_drill

    Truck-mounted core drill. A modern core drill is a drill specifically designed to remove a cylinder of material, much like a hole saw. The material left inside the drill bit is referred to as the core. Core drills used in metal are called annular cutters. Core drills used for concrete and hard rock generally use industrial diamond grit as the ...

  5. Why Costco is selling gold bars and silver coins

    www.aol.com/why-costco-selling-gold-bars...

    The coins are non-refundable, and members can purchase a maximum of five. Costco is trying to replicate its recent success with gold bars. It began selling $2,000 gold bars online in September and ...

  6. Metallurgical assay - Wikipedia

    en.wikipedia.org/wiki/Metallurgical_assay

    A coin assayer is often assigned to each mint or assay office to determine and assure that all coins produced at the mint have the correct content or purity of each metal specified, usually by law, to be contained in them. This was particularly important when gold and silver coins were produced for circulation and used in daily commerce. Few ...

  7. Exploration diamond drilling - Wikipedia

    en.wikipedia.org/wiki/Exploration_diamond_drilling

    The drill uses a diamond encrusted drill bit (pictured on the right) to drill through the rock. The drill produces a "core" which is photographed and split longitudinally. Half of the split core is assayed, while the other half is permanently stored for future use and re-assaying if necessary. Although a larger diameter core is the most ...