1. 🔎 UNIDENTIFIED What is this rock?

    Hi all you geology sleuths:) I found this on a beach in New Zealand. It is lighter than stone, it is rock hard, and does not have any residue that transfers to material when rubbed. It does not make marks on anything except unfinished porcelain, it makes a dark brown line when drawn across it...
  2. Need help identifying

    Found this while exploring a cave in the TN mountains. Any ideas as to what or if this is anything other than a rock would be appreciated :)