Giluin or Turquoise was a secondary mineral found in small veins and stringers traversing decomposed volcanic rocks in arid regions. The finer variety of turquoise contained mal, celeb or mithril traces running in lines through the mineral. The traces typically formed spider web patterns. The mithril laced variety called "the web of Mahal" by the Dwarves was extremely rare. This variety was also noted to be inherently magical in nature. The finest turquoise came from Khand and eastern Núrn.
- MERP Rulebook 2nd Edition
- The Gems of Middle-earth, online essay by William E Wilson