Pyrite
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- Lustre:Metallic
- Transparency:Opaque
- Colour:Pale brass-yellow
- Streak:Greenish-black
- Hardness:6 - 6½ on Mohs scale
- Tenacity:Brittle
- Cleavage:Poor/Indistinct Indistinct on {001}.
- Fracture:Irregular/Uneven, Conchoidal
One of the most common semiconducting minerals, pyrite exhibits high conductivity and easily provides a voltage drop - often in both polarities equally, rectification is harder to find than some minerals. More decayed material seems to perform better than freshly exposed or well crystallised pyrite. The crustiest and worst (massive) crystallisation the better it seems to be, for our purposes.
Pyrite seems to vary quite widely across different localities. Material from Nangiles mine near Bissoe seems to provide particularly noisy point contact junctions - great for use in the noisegen, perhaps due to decay and formation of marcasite. Otherwise this mine is fairly recent, shutting only in the early 90s. In comparison, pyrite from the much older Wheal Lovelace (perhaps under a kilometer away) is much better preserved, formed from euhedral crystals - but is harder to use effectively.