Definition: Extractive Goods (Comtrades HS-Categorization)
I know this is a little late, (just joined this forum two hours ago) but if it is still relevant. You should look at the Australian Department of Foreign Affairs and Trade TRIEC system (Google "DFAT TRIEC") It is an established system and useful for high level groupings. You might try to use their groupings and hopefully be able to answer the questions from the analysis.