Linked from
The 15 pages that link to Pyrite, each with the reason it gives.
Lapis lazuliRelated: Its gold-colored flecks are a familiar feature of many lapis specimens.
Oxidation zoneRelated: Its oxidation can produce acidity and ferric iron that attack other sulfides.
WheellockRelated: Wheellock jaws held pyrite against the turning wheel to create ignition sparks.
LazuriteRelated: Tiny pyrite grains commonly accompany lazurite in lapis lazuli.