Lab
It is term used for a room or complex which contains all the scientific equipment required for research and tests.

Labradorescence
It is an effect that cause dark, metallic-like color shimmer, usually blue and green, to be displayed on a few minerals. The name has been taken from Labradorite mineral that gives the best effect.

Laccolith
It is the lenticular mass of an igneous rock that is stuck between layers of sedimentary rock.

Laminated rock
It is the sedimentary rocks having many thin layers.

Lava
It is the name given to molten rock on earth's surface that is released from a volcano.

Leach
It is a chemical process where certain components of the ore are dissolved in order to extract and concentrate valuable minerals.

Lenticular
It is term used for the lens shaped body of rock.

Light
It is a type of an electromagnetic radiation which oscillates between the electric and magnetic fields, and it can be detected by the human eye.

Light refraction
See refraction.

Light reflection
See reflection.

Limestone
It is a name given to any sedimentary rock which consists mostly of carbonates, calcite and/or dolomite.

Litmus paper
It is a paper with extraction of powder from certain plants to test the pH of a substance. In it acid turns red and base turns blue; neutral remains white. The intensity of the change color depends upon the concentration of the acid or base.

Lode
It is a mining term used for mineralized vein. The term is used irrespective of whether the vein can be economically extracted.

Longwall mining
It is a type of mining which is typically found in an underground coal mines. The coal seam is extracted mechanically and the 'hanging wall' is allowed to collapse to fill in the void under controlled conditions. The collapsed 'hanging wall' material is called 'goaf.'

Longwave (LW)
It is a wavelength of UV light. Some of the minerals display fluorescence after being exposed to the UV light.

Luster
It is the exhibition of the surface of minerals, which also includes their reflective properties. Different terms applied to luster are as follows:

• Metallic or splendit
  
• Submetallic
  
• Vitreous or glassy
  
• Adamantine or brilliant or diamondlike
  
• Resinous or resinlike
  
• Silky
  
• Pearly or mother-of-pearl
  
• Greasy or oily
  
• Pitchy or pitchlike
  
• Waxy or waxlike
  
• Dull or earthy