It crystallizes in the monoclinic prismatic system and typically occurs as vitreous bright yellow to red botryoidal to reniform masses and radiating crystal prisms. Its specific gravity is 2 to 2.1 and its Mohs hardness is 2.
It occurs in arid climates as a secondary alteration product of pyrite-bearing deposits.
- Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy, (7th edition), v. II, pp. 617–618.
- Mineral Data Publishing (PDF)
- Mindat with locality data
- Webmineral data
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