Miguelromeroite
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| Miguelromeroite | |
|---|---|
 | |
| General | |
| Category | Minerals |
| Formula | Mn5(AsO4)2(HAsO4)2 · 4H2O |
| IMA symbol | Mig[1] |
| Crystal system | Monoclinic |
| Crystal class | Prismatic H-M symbol: 2/m |
| Space group | B2/b |
| Unit cell | 1,624.38 |
| Identification | |
| Color | Salmon pink to orange |
| Twinning | None observed |
| Cleavage | Good on {100} |
| Fracture | Conchoidal |
| Mohs scale hardness | 4 |
| Luster | Vitreous |
| Streak | Pale pink |
| Diaphaneity | Transparent |
| Density | 3.69 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.713 nβ = 1.723 nγ = 1.729 |
| Birefringence | 0.016 |
| Pleochroism | Visible |
| 2V angle | Measured: 70° Calculated: 75° |
Miguelromeroite is a mineral named for Miguel Romero Sanchez by Anthony Robert Kampf. The mineral, first described in 2008[2] was named in 2009, the same year it got approved by the International Mineralogical Association.
Miguelromeroite is a member of the hureaulite group, and is the manganese analogue of the mineral sainfeldite. It is known as a synthetic compound,[3] and was originally labeled as villyaellenite due to the very rare complex arsenate microcrystals.[2] It shows pleochroic attributes, which is an optical phenomenon that makes gems to be seen a different color depending on the axis it is being inspected. Viewing it from the Z axis, the mineral can be seen in a pale pink color. It was redefined as an intermediate species of the series. It is the full magnesium endmember of the series. Crystals are up to 4 cms in length, and are elongated on [001] with forms {100}, {110} and {101̅}.[4]