1. Dripstone
   1. Stalactite
      1. water drips from roof
      2. leaves behind calcite
      3. develops into a tube
         1. straw stalactite
      4. tube forms full stalactite
   2. Stalagmites
   3. Curtains
   4. Pillars
2. Calcite
   1. formed from
      1. calcium carbonate
   2. Pure
      1. white
   3. impure
      1. discoloured
3. Topic