Sunday, December 29, 2013

Underground Mine Development

Directional Terms 

Breast - Advancing in a near - horizontal direction , also the working face of an opening 
Inby - Towards the working face , away from the mine entrance 
Outby - Away from the working face , towards the entrance
Overhand - Advancing in an upward direction 
Underhand - Advancing in downward direction 


Excavation Terms 

Adit - main horizontal or near - horizontal underground opening , with single access to the surface
Bell - funnel shaped excavation formed at the top of a raise to move bulk material by gravity from a stop to a drawpoint 
Bleeder - Exhaust ventilation lateral 


Underground Mine Development

Terms 

Deposit and Spatial Terms 

Back - roof , top , or overlying surface of an underground excavation
Bottom - floor or underlying surface of an underground excavation
Capping - waste material overlying the mineral deposit 
Country rock - waste material adjacent to a mineral deposit
Crown pillar - portion of the deposit overlying an excavation and left in place as a pillar 
Dip - angle of inclination of a deposit , measure from the horizontal,  also pitch or attitude 
Floor - Bottom or Underlying surface of an underground excavation
Footwall -   wall rock under the deposit
Gob - Broken , caved , and mined out portion of the deposit
Hanging wall - wall rock above the deposit
Pillar - unmined portion of the deposit , providing support to the roof or hanging wall 
Rib - Side wall of an excavation , also rib pillar
Roof - back , top , or overlying surface of an excavation 
Sill pillar - portion of the deposit underlying an excavation and left in place as pillar 
Strike - Horizontal bearing of a tabular deposit as its surface intersection
Wall rock - Country rock boundary adjacent to the deposite


Tuesday, December 3, 2013

Gemmology

Essential qualities of a gem material 
               
  1. Beauty
o   Colour

o   Clarity


 2 .  Rarity

Stones with special optical effects



Chatoyancy - Cat's eye


Asterism - Star sapphire


Play of colour - Opal


Adulresecence - Moonstone



Labradorecence - Labradorite 



 3. Durability/ Hardness



Classification of gem materials 

  • Minerals - inorganic origin 
  • organic gem materials
  • Man made products