Potassic-arfvedsonite (original) (raw)

RI values:

_n_α = 1.683(2) _n_β = 1.692(2) _n_γ = 1.699(2)

2V:

Measured: >60° , Calculated: 82°

δ = 0.016

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Dispersion:

Strong, r > v.

Optical Extinction:

Z = b, X ∧ c = 20(10)°, Y ∧ a = 30(10)°.

Comments:

X = dark blue-green, Y = gray-green, Z = pale green-gray to pale green-brown.

Comments:

Absorption: X ≥ Y > Z.

Crystal System:

Monoclinic

Class (H-M):

2/m - Prismatic

Cell Parameters:

a = 10.002(2) Å, b = 18.054(3) Å, c = 5.319(1) Å
β = 103.9(3)°

Ratio:

a:b:c = 0.554 : 1 : 0.295

Unit Cell V:

932.36 ų (Calculated from Unit Cell)

Co-Type Localities:

ⓘ Potassic-Arfvedsonite occurrence, Pegmatite Valley, Lilleelv, Head of Kangerluarsuk, Kangerluarsuk Fjord, Ilímaussaq complex, Kujalleq, Greenland
ⓘ Hilairitovoye pegmatite, 252 m level, Kirovskii apatite mine, Kukisvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
ⓘ Palitra pegmatite, Karnasurt mine, Karnasurt Mountain, Lovozersky District, Murmansk Oblast, Russia

General Appearance of Type Material:

Euhedral, prismatic to acicular crystals from a few centimeters to 15 x 0.8 cm.

Place of Conservation of Type Material:

Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, no. 3137/1 (Greenland) and 3137/2 (Lovozero).

Empirical Formula of Type Material:

(K0.67Na0.22) 0.89(Na1.95Ca0.05) 2.00 (Fe2+ 3.29Fe3+ 1.26Li0.29Mn0.19Ti0.05Zn0.02Mg0.01) 5.11(Si7.76Fe3+ 0.13Al0.11) 8.00 O22[(OH) 1.81F0.18] 1.99

Geological Setting of Type Material:

Associated Minerals at Type Locality:

IR Spectrum:

The IR spectrum contains bands (sh = shoulder) at (cm-1) 3700, 3675, 1134, 1076, 1025 sh, 990 sh, 957, 900 sh, 741, 692, 661, 643, 520 sh, 491, 445 and 430 sh.

Health Risks:

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