UNAPPRECIATED DEFICIENCIES. Sulfur is found in a large number of foods, and, as a consequence, it is assumed that almost any diet would meet the minimum daily requirements. Excellent sources are eggs, onions, garlic, and leafy dark green vegetables like kale and broccoli. Meats, nuts, and seafood also contain sulfur.
Normal Mode Ores. 1  Copper or Tin. 2  Iron or Lead. 3  Silver or Tungsten.  Gold or 1  Platinum. Demonite or Crimtane - Corruption/Crimson - Gold or better Pickaxe required.  Meteorite - Tungsten or better Pickaxe 1  required. Obsidian - formed when water meets 2  lava. Hellstone - found in the Underworld  only.
In the same fashion of this question, you can't mine Crimstone Block prior of making a fifth tier pickaxe, for example Deathbringer pickaxe (Nightmare pickaxe for the Corruption biomes). Thus you're right in saying that you need Tissue Sample, which is looted on the Brain of Ctlulhu.