Britvinite, a new mineral species, has been found in manganese ore at the Långban deposit, Bergslagen ore district, Filipstad,
Värmland County, Sweden. Calcite, barytocalcite, brucite, cerussite, and hausmannite are associated minerals. Britvinite occurs
as pale yellow to colorless transparent plates with a white streak up to 0.2 × 0.5 × 0.5 mm in size, which are flat parallel
to {001}; the luster is adamantine. Thin lamellae are flexible, whereas thick ones are brittle; the Mohs hardness is 3. The
cleavage is eminent parallel to {001}. The calculated density is 5.51 g/cm
3. In the infrared spectrum of the new mineral, the bands of (OH)−, (CO
3)
2−, and (BO
3)
3− are recorded, whereas those corresponding to water molecules are absent. Britvinite is optically biaxial and negative, α
= 1.896(2), β = 1.903(2), γ = 1.903(2), 2
Vmeas = 20(10),
Z≈
c. Dispersion is strong,
r<
v. The chemical composition (electron microprobe; H
2O determined with the Alimarin method, CO
2, with selective sorption) is (wt %) 7.95 MgO, 71.92 PbO, 0.41 Al
2O
3, 12.77 SiO
2, 2.2 H
2O, 2.1 CO
2, 2.67 B
2O
3 (calculated on the basis of structural data); total 100.02. The empirical formula calculated on the basis of 59 anions (O
+ OH) (
Z = 1) is as follows: Pb
14.75Mg
9.03Si
9.73Al
0.37O
30.76(BO
3)
3.51(CO
3)
2.18(OH)
11.7. The simplified formula (
Z = 2) is Pb
7 + x
Mg
4.5(Si
5O
14)(BO
3)
2(CO
3)(OH,O)
7 (
x < 0.5). The crystal structure of britvinite has been studied on a single crystal at 173 K;
R = 0.0547. The new mineral is triclinic, space group
P
$
\bar 1
$
\bar 1
; the unit-cell dimensions are
a = 9.3409(8),
b = 9.3597(7),
c = 18.8333(14) Å, α = 80.365(6)°, β = 75.816(6)°, γ = 59.870(5)°,
V = 1378.74(19) Å
3. The structure consists of alternating
TOT stacks (containing octahedral brucite-like and discontinuous tetrahedral (Si
5O
14)
∞∞ layers) and multilayered [Pb
7.1(OH)
3.6(CO
3)(BO
3)
1.75(SiO
4)
0.25]
∞∞ blocks. The strongest reflections in the X-ray powder diffraction pattern [
d, Å (
I, %)(
hkl)] are 18.1(100)(001), 3.39(30)(12
$
\bar 3
$
\bar 3
, 1
$
\bar 1
$
\bar 1
4, 015), 3.02(90)(006, 130, 106, 2
$
\bar 1
$
\bar 1
0, 1
$
\bar 2
$
\bar 2
1), 2.698(70)(332, 134, 030, 1
$
\overline {23}
$
\overline {23}
), 2.275(30)(008, 420, 424), 1.867(30)(446, 239, 2.1.10, 1
$
\bar 2
$
\bar 2
8), 1.766(40)(151, 31
$
\bar 7
$
\bar 7
, 1
$
\bar 4
$
\bar 4
0, 453, 542, 512, 4
$
\bar 1
$
\bar 1
2), 1.519(40)(0.0.12). The mineral has been named in honor of Sergei Nikolaevich Britvin (b. 1965), a Russian mineralogist.
The type material of britvinite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow. The
registration number is 3458/1.