Wöhlerite (original) (raw)

Formula:

Na2Ca4ZrNb(Si2O7)2O3F

Colour:

Honey-yellow, wine-yellow to sulfur-yellow, light to dark yellow, brown, gray

Specific Gravity:

3.40 - 3.44

Crystal System:

Monoclinic

Name:

Named after the German chemist Friedrich Wöhler (31 July 1800, Eschersheim, Landgraviate of Hesse-Kassel, Holy Roman Empire - 23 September 1882, Göttingen, German Empire), professor of chemistry in the University of Göttingen (Germany). He was the first to isolate the chemical elements beryllium and yttrium in pure metallic form.

First described by Scheerer (1843) from several syenite pegmatites in Langesundsfjorden, Norway, among them Løvøya. The exact type locality is not known, but since Løvøya was mentioned specially by Scheerer (1843) this island has become listed as the type locality in several publications.

The crystal structure was solved by Mellino & Merlino (1979) on a sample from "Brevig" (= Langesundsfjorden, Norway).

Occurs in syenite pegmatite, syenites and carbonatites.

Transparency:

Transparent, Translucent

Colour:

Honey-yellow, wine-yellow to sulfur-yellow, light to dark yellow, brown, gray

Streak:

Yellowish white; pale yellow

Cleavage:

Distinct/Good
Distinct on {010}
Poor on {100}{110}

Fracture:

Irregular/Uneven, Splintery

Density:

3.40 - 3.44 g/cm3 (Measured) 3.42 g/cm3 (Calculated)

RI values:

_n_α = 1.700 - 1.705 _n_β = 1.716 - 1.720 _n_γ = 1.726 - 1.728

2V:

Measured: 70° to 77°, Calculated: 70° to 76°

δ = 0.026

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

Optical Extinction:

Z = b; X ∧ c = 45°.

Comments:

X=Y= nearly colorless to pale yellow
Z= wine-yellow

Crystal System:

Monoclinic

Class (H-M):

2 - Sphenoidal

Cell Parameters:

a = 10.823(3) Å, b = 10.244(3) Å, c = 7.290(2) Å
β = 109.00(4)°

Ratio:

a:b:c = 1.057 : 1 : 0.712

Unit Cell V:

764.21 ų (Calculated from Unit Cell)

Morphology:

Prismatic crystals to 3 cm, granular. Thick tabular on {100}. Brøgger (1890) list these forms as the more frequent ones {100}, {110}, {210}, {120}, {130}, {001}, {101}, {101}, {111} and {011}. Other forms observed are {010}, {720}, {012}, {021}, {111}, {121}, {311}, {201}, {212}, {121}, {211}, {221} and {161}.

Twinning:

Twin plane {010} common; may be complex, lamellar.

- 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.