| Feroxyhyte | |
|---|---|
| General | |
| Category | Mineral |
| Chemical formula | δ-Fe3+O(OH) |
| Strunz classification | 04.FE.40 |
| Dana classification | 06.01.04.04 |
| Unit cell | a = 2.95 Å, c = 4.56 Å; Z = 1 |
| Identification | |
| Molar mass | 88.85 g |
| Color | Brown, yellow-brown |
| Crystal habit | Concretionary, massive, nodular |
| Crystal system | Hexagonal |
| Streak | Yellow |
| Diaphaneity | Opaque |
| Specific gravity | 4.31 |
| Density | 4.2 |
| Optical properties | Uniaxial |
| References | [1][2][3] |
Feroxyhyte is an oxide/hydroxide of iron, δ-Fe3+O(OH). Feroxyhyte crystallizes in the hexagonal system. It forms as brown rounded to concretionary masses. Feroxyhyte is opaque, magnetic, has a yellow streak, and has a relative density of 4.2.[2]
It occurs in manganese-iron nodules on the Atlantic and Pacific Ocean floors. It is also found in the Baltic, White, and Kara Seas.[4] Forms under high pressure conditions and reverts to goethite on exposure to surface conditions.[2] It also occurs as cement and coatings on clasts in poorly drained soils and sediments, formed by the rapid oxidation of iron(II) oxide compounds.[4]
It was first described in 1976 for an occurrence in soils at its type locality: Kolomyya, Ivano-Frankivsk Oblast, Ukraine.[1][4]