Kidwellite
| Kidwellite | |
|---|---|
| General | |
| Category | Minerals |
| Formula | NaFe3+9+x(PO4)6(OH)4·12H2O (x ≈ 0.33) |
| IMA symbol | Kdw |
| Strunz classification | 08.DK.20 |
| Dana classification | 42.08.02.01 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic
H-M Symbol: 2/m |
| Space group | P2/c |
| Unit cell | 1,393.77 |
| Identification | |
| Formula mass | 1,368.34 |
| Color | Greenish white, light green, greenish yellow, yellow |
| Cleavage | Perfect on {100} |
| Fracture | Splintery |
| Mohs scale hardness | 3 |
| Luster | Resinous, waxy, silky, dull |
| Streak | Yellow |
| Diaphaneity | Translucent |
| Specific gravity | 3.04 – 3.3 |
| Density | Measured: 3.04 – 3.3 Calculated: 3.34 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.787 nβ = 1.800 nγ = 1.805 |
| Birefringence | 0.018 |
| Pleochroism | None |
| Dispersion | Extreme |
| Ultraviolet fluorescence | None |
| Common impurities | Aluminum, Copper, Arsenic |
Kidwellite in an uncommon mineral that was discovered in Arkansas in the United States. It was approved by the IMA in 1974, but it was only named in 1978 by Moore and Ito after Albert Lewis (Laws) Kidwell.