What is the relationship between Norsk Hydro and aluminium in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

Norsk Hydro (LSE: NHY.L - news ) shares rose 2.8 percent, the top gainer in the pan-European FTSEurofirst 300 index, after the aluminium maker posted second-quarter operating earnings above expectations in spite of weaker metal prices.

Answer: product_or_material_produced