Rock & Gem Kids is a monthly feature that offers articles, puzzles, and a quiz with prizes for junior rockhounds.
1. Black zinc sulfide, which has a high iron content, is called marmatite or, informally, “black jack” .
2. Eurypterids belong to the sea scorpion family, but were more closely related to horseshoe crabs .
3. Sphalerite is the principal ore of zinc .
4. Minerals that come in the dendritic form are copper, silver, gold and pyrolusite.
5. Double refraction is an optical property of Iceland spar.