Yingjiangite
General
Category	Mineral
Formula (repeating unit)	K2Ca(UO2)7(PO4)4(OH)6 · 6H2O
IMA symbol	Yin[1]
Strunz classification	8.EC.10
Dana classification	42.6.12.1
Crystal system	Orthorhombic
Crystal class	Dipyramidal H-M Symbol: mmm (2/m 2/m 2/m)
Unit cell	3,747.21
Identification
Color	Yellow, golden yellow
Cleavage	None observed
Tenacity	Brittle
Mohs scale hardness	3 - 4
Luster	Subadamantine, subvitreous, rsinous
Streak	Yellow to pale yellow
Specific gravity	4.15
Density	4.15
Optical properties	Biaxial (-)
Refractive index	nα = 1.666 - 1.669 nβ = 1.692 - 1.703 nγ = 1.707 - 1.710
Birefringence	0.041
Pleochroism	Visible
2V angle	Measured: 36°- 38° Calculated: 36°
Dispersion	r > v or r < v
Extinction	Parallel
Ultraviolet fluorescence	Fluorescent
Common impurities	Na, Mg, Mn, Fe, Ti, Si
Other characteristics	Radioactive

Yingjiangite is a mineral named after its type locality in the Yingjiang county in 1990. It is a member of the phosphuranylite group, although the species was doubted by two geologists. It is easily confused with phosphuranylite, though the two geologists (José Moacyr Vianna Coutinho and Daniel Atencio) claim that the mineral might be identical to it, even though yingjiangite was approved in 1989-1990 by the IMA.^[2]

Properties

This mineral has pleochroic attributes, which is an optical phenomenon that makes the mineral seem to be a different color depending on the axis it is inspected on. On the x axis, the mineral seems to be almost colorless, on the y it is pale yellow, and on the z it can be seen as a yellow mineral.^[2] It is also fluorescent, meaning that it emits light when exposed to a certain type of light (in most cases ultraviolet), or either when it absorbs electromagnetic radiation. The fluorescent attribute of is due to the mineral being uranium based. Both under short and long UV light, it emits a weak yellow green light.^[3] Yingjiangite grows in acicular crystals up to a millimeter. It forms aggregates, made of clusters or several individual crystals. It has a fine-grained coating and yellow crusts. A common finding place for the mineral is in uranium deposits, especially in oxidized zones, as it is a uranium and oxygen-based mineral.^[2] It is a secondary product in these mines, which in most of the cases contain uraninite and uranothorite. Yingjiangite mostly consists of uranium (63.90%) and oxygen (25.77%), but otherwise includes phosphorus (4.75%), potassium (4.50%), hydrogen (0.70%) and calcium (0.38%). Due to the high uranium concentration of the mineral, it has a very strong, 4,679,034.10 radioactivity measured in Gamma Ray American Petroleum Institute Units. The concentration per GRapi unit of the mineral is 213.72.^[3]

References