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Unnamed (Cl-analogue of Annite)

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Formula:
KFe2+3(AlSi3O10)(Cl,OH)2
Colour:
grayish brown
Lustre:
Silky
Hardness:
3
Specific Gravity:
3.421 (Calculated)
Crystal System:
Monoclinic
This page provides mineralogical data about Unnamed (Cl-analogue of Annite).


Hide all sections | Show all sections

Unique IdentifiersHide

Mindat ID:
472353
Long-form identifier:
mindat:1:1:472353:6

Physical Properties of Unnamed (Cl-analogue of Annite)Hide

Silky
Transparency:
Translucent
Colour:
Grayish brown
Streak:
Colorless
Hardness:
Tenacity:
Brittle
Cleavage:
Perfect
{001}
Density:
3.421 g/cm3 (Calculated)

Chemistry of Unnamed (Cl-analogue of Annite)Hide

Mindat Formula:
KFe2+3(AlSi3O10)(Cl,OH)2
Element Weights:
Element% weight
Fe30.529 %
O29.155 %
Si15.354 %
Cl12.921 %
K7.125 %
Al4.917 %

Calculated from ideal end-member formula.

Crystallography of Unnamed (Cl-analogue of Annite)Hide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 5.3991(4) Å, b = 9.3586(6) Å, c = 10.2421(10) Å
β = 100.873(9)°
Ratio:
a:b:c = 0.577 : 1 : 1.094
Unit Cell V:
508.22 ų (Calculated from Unit Cell)
Z:
2

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) 7.1247% 2,209 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 Unnamed (Cl-analogue of Annite)Hide

References for Unnamed (Cl-analogue of Annite)Hide

Localities for Unnamed (Cl-analogue of Annite)Hide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Russia
 
  • Krasnoyarsk Krai
    • Taymyrskiy Autonomous Okrug
      • Taimyr Peninsula
        • Norilsk-Talnakh Mining Region
Barkov et al. (2025)
          • Talnakh Cu-Ni Deposit
Barkov et al. (2025)
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