Why margin requirement for commodities like alumini, copper mini is low?

why margin requirement for commodities like alumini ,copper mini is low as rs 4000(mis) when 1rs change can lead to profit or loss of rs 1000 ?

Dear Sir,

Margin Requirement for any commodity contract is fixed based on the volatility of particular script. even though if 1Rs change is Copper can lead to profit or loss of rs 1000. these commodities tend to move slow compared to other commodities.

for example if silver can fluctuate more than 4% in a given period, where as copper can fluctuate only 2.5% in the same time period. means to say price movement is slow as compared with silver or crude oil price movement or any other commodities.