• In general the energy required to produce a material is a large factor in the raw material cost. As a result most materials lie on a line from bottom left (low cost/low energy content) to top right (high cost/large energy content).
  
  
• It is difficult to assess the environmental impact of using one material over another since there are many factors from production to disposal.
  
• The energy content used to produce a material gives a rough indication of the environmental cost of production
• For materials which are energy intensive to produce there are large cost and energy savings by recycling e.g. aluminium cans
• Gold is a precious metal which can be sold for a very high price; this means that more energy can be spent in extracting it by mining rocks containing only a small fraction of gold

• the energy required to collect/mine the material.
• the energy required to refine, extract or synthesise it.

;dtdm hojdhv hgl,h] vs,lhj ,av,p gglrhvkm energy required to produce a material