Question

sources of pyrite

Answer 1

Do you mean natural/geologic sources (where pyrite occurs in nature) or commercial sources (where to buy pyrite specimens)? Below I summarize both.

Natural/geologic sources and formation environments
- Sedimentary/diagenetic deposits
- Authigenic pyrite forms in anoxic (reducing) sediments where dissolved Fe2+ reacts with H2S produced by bacterial sulfate reduction. Common in shales, black muds, and some sandstones and limestones. Often appears as framboidal or disseminated grains and nodules.
- Hydrothermal veins and sulfide deposits
- Pyrite is abundant in high- and low-temperature hydrothermal systems, often in veins and stockworks. Typical in volcanogenic massive sulfide (VMS) deposits and epithermal veins.
- Magmatic and magmatic-hydrothermal
- Disseminated pyrite can occur in igneous rocks and related magmatic-hydrothermal systems.
- Metamorphic rocks
- Pyrite commonly survives metamorphism or forms by recrystallization in metamorphic schists and gneisses.
- Coal and fossil-bearing rocks
- Common in coal seams and associated mudstones; forms as concretions or disseminated grains.
- Supergene/oxidation zones (secondary)
- Weathering of sulfide minerals can leave iron oxides and secondary sulfates; pyrite itself can be preserved in reduced pockets or may be partially oxidized.

Typical host rocks and associations
- Host rocks: shale, mudstone, sandstone, limestone, coal, hydrothermal vein-hosting rocks, metamorphic schists.
- Commonly associated minerals: chalcopyrite, sphalerite, galena, arsenopyrite, marcasite, and gold (gold can occur as inclusions in pyrite).

Morphologies
- Framboidal (spherical aggregates of microcrystals) — common in sediments.
- Euhedral cubic or pyritohedral crystals — common in hydrothermal and pegmatitic settings.
- Massive, nodular, or disseminated forms.

Why pyrite is important
- Indicator mineral for certain ore deposits (e.g., VMS, epithermal) and sometimes associated with gold.
- Source of acid mine drainage when oxidized (environmental concern).
- Common component of sedimentary organic-carbon burial and diagenetic processes.

Notable localities (examples)
- Rio Tinto, Spain (historic massive sulfides)
- Cornwall, England (hydrothermal veins)
- Various VMS districts (e.g., British Columbia, Canada)
- Coalfields worldwide where pyritization occurred
- Many mine districts in the USA, Canada, Peru, China, Poland, Sweden, etc.

Commercial/collecting sources
- Mineral and rock shops, online marketplaces (e.g., mineral dealers, Etsy/eBay), museum shops, gem & mineral shows.
- When buying, note that some “pyrite” jewelry may be treated or mixed with other sulfides; check seller descriptions.

If you want more detail, tell me whether you mean geologic formation processes, specific mines/localities, or places to purchase specimens.