plank

Hello everyone, I found some rocks in my childhood, kept them for 20 years and now I need to know what they are made of (in case they would harm my gecko), Any gess of what if could be ? or maybe experiments to help (vinager, magnet, ..) ? 1. bleu, purple, gold, white(solid) 2. dark brown, verry spongious volcanic like 3. black melted like shape, dark gold like depot 4. Iron like, melted shape with cracks link to rocks images : https://postimg.cc/gallery/B0W35Jq (I can provide more photo if needed) Thank you for your help !