| Feroxyhyte | |
| Category: | Oxide mineral |
| Formula: | δ-Fe3+O(OH) |
| Imasymbol: | Fox[1] |
| Strunz: | 4.FE.40 |
| Dana: | 06.01.04.04 |
| Unit Cell: | a = 2.95, c = 4.56 [Å]; Z = 1 |
| Molweight: | 88.85 g/mol |
| Color: | Brown, yellow-brown |
| Habit: | Concretionary, massive, nodular |
| System: | Hexagonal Unknown space group |
| Streak: | Yellow |
| Diaphaneity: | Opaque |
| Gravity: | 4.31 |
| Density: | 4.2 |
| Opticalprop: | Uniaxial |
| References: | [2] [3] [4] |
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.[3]
It occurs in manganese-iron nodules on the Atlantic and Pacific Ocean floors. It is also found in the Baltic, White, and Kara Seas.[5] Forms under high pressure conditions and reverts to goethite on exposure to surface conditions.[3] 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.[5]
It was first described in 1976 for an occurrence in soils at its type locality: Kolomyya, Ivano-Frankivsk Oblast, Ukraine.[2] [5]