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Calcioandyrobertsite-2O

A structural variant of Calcioandyrobertsite
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Formula:
KCaCu5(AsO4)4(H2AsO4) · 2H2O
Colour:
Intensely blue
Lustre:
Vitreous
Hardness:
3 - 4
Specific Gravity:
3.9
Crystal System:
Orthorhombic
A polytype of Calcioandyrobertsite


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Unique IdentifiersHide

Mindat ID:
54119
Long-form identifier:
mindat:1:1:54119:6

Physical Properties of Calcioandyrobertsite-2OHide

Vitreous
Transparency:
Transparent
Colour:
Intensely blue
Streak:
Pale blue
Hardness:
3 - 4 on Mohs scale
Hardness Data:
Measured
Tenacity:
Brittle
Cleavage:
Distinct/Good
On {100]
Density:
3.9(1) g/cm3 (Measured)    3.80(1) g/cm3 (Calculated)

Optical Data of Calcioandyrobertsite-2OHide

Type:
Biaxial (-)
RI values:
nα = 1.715(5) nβ = 1.730(5) nγ = 1.735(5)
2V:
Measured: 55° (5), Calculated: 60°
Max. Birefringence:
δ = 0.020
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.

Surface Relief:
Moderate
Pleochroism:
Visible
Comments:
γ = intense blue, β = blue, α= pale blue.

Chemistry of Calcioandyrobertsite-2OHide

Mindat Formula:
KCaCu5(AsO4)4(H2AsO4) · 2H2O
Element Weights:
Element% weight
As33.164 %
O31.162 %
Cu28.129 %
Ca3.548 %
K3.461 %
H0.535 %

Calculated from ideal end-member formula.

Crystallography of Calcioandyrobertsite-2OHide

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Pnma
Cell Parameters:
a = 19.647(2) Å, b = 10.087(1) Å, c = 9.903(1) Å
Ratio:
a:b:c = 1.948 : 1 : 0.982
Unit Cell V:
1,962.57 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Elongated along [011] or [001], platy on {100}.
Twinning:
None observed.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
9.80 Å(50)
7.084 Å(70)
6.665 Å(60)
4.830 Å(70)
4.487 Å(90)
3.965 Å(60)
3.116 Å(100)
2.760 Å(90)
2.674 Å(40)
1.758 Å(40)

Synonyms of Calcioandyrobertsite-2OHide

RadioactivityHide

Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 0.0000% 0 α, β, γ
Thorium (Th) 0.0000% 0 α, β, γ
Potassium (K) 3.4614% 1,073 β, γ

For comparison:

  • Banana: ~15 Bq per fruit
  • Granite: 1,000–3,000 Bq/kg
  • EU exemption limit: 10,000 Bq/kg

Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.

Interactive Simulator:

Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!

Activity: –

DistanceDose rateRisk
1 cm
10 cm
1 m

The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).

D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for Calcioandyrobertsite-2OHide

References for Calcioandyrobertsite-2OHide

Quick NavTopUnique IdentifiersPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionSynonymsRadioactivityOther InformationInternet Links References
 
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