Mining-Prospecting Dictionary

• Lacustrine deposit: Sedimen ts deposited on the bottom of lakes.
• Lagging: Small timbers or planks used in underground mines; also spikes used to nail timbers together.
• Launder: A device for cleaning lighter waste materials form ore
• Lay: The general direction or slope of a device or ground surface.
• Layback: The amount of material which must be mined for the slope of a pit wall to be at a safe angle
• Leach: Mineral extraction by dissolving minerals in solution.
• Leaching: The extraction of a soluble metallic compound from ore by dissolving the metals in a solvent. See also Heap Leaching.
• Leach Cycle: The average amount of time that ore is leached.
• Leach Pad: A large, impermeable foundation or pad used as a base for ore during Heap Leaching. The pad prevents the leach solution from escaping out of the circuit.
• Dedicated Pad: A leach pad that is constructed to permanently accommodate one ore heap. The pad forms the tailings pile when economic recovery has been reached and the pad neutralized.
• Reusable Pad: A pad where ore is loaded and then unloaded at the end of each Leach Cycle. The pad, made of durable materials, can be reused continually.
• Lead: The bottom portion of gold-bearing channel gravels, particularly in buried placers.
• Ledge: A horizontal layer of rock.
• Legal Tender: The coin or currency which the monetary authority of the issuing country declares to be universally acceptable therein as a medium of exchange; acceptable in the discharge of debts.
• Lens: A mineral deposit shaped like an eyeglass lens.
• Lessee: The person leasing or optioning a mining property
• Level: A horizontal tunnel or drift in an underground mine.
• Leverage: In futures, the advantage allowed an investor by depositing funds that are less than the value of the contract.
• Linear: Al ong the length of an object or area.
• Liquidity (or Liquid Market): The quality of being readily convertible into cash. Refers to the least cost at which one can enter and then close out a position. A broadly traded market where buying and selling can be accomplished with small price changes.
• Lode: A relatively confined mineral deposit lying within a rock formation.
  "London Fix": Twice-daily bidding session in London of the five major gold traders, at which the price is fixed or set. The London Fix is the basis for many gold contracts worldwide.
• Long-hole open stop: A method of mining involving the drilling of holes up to 90 feet long into an orebody and then blasting a slice of rock which falls into an open space. The broken rock is extracted and the resulting open chamber is not filled with supporting material.
• Long and Short: A trader is long if he purchases more metal or futures contracts than he sells. Conversely, he is short if he sells more than he buys.
• Long tom: A small, portable sluice for washing placer gravel, usually built in several sections.
• Luster: The character of light reflected by minerals.