TY - JOUR

T1 - Grootfonteinite, Pb3O(CO3)2, a new mineral species from the Kombat Mine, Namibia, merotypically related to hydrocerussite

AU - Siidra, O.I.

AU - Jonsson, Erik

AU - Chukanov, N.V.

AU - Nekrasova, D.O.

AU - Pekov, I.V.

AU - Depmeier, Wulf

AU - Polekhovsky, Y.S.

AU - Yapaskurt, V.O.

PY - 2018/4/1

Y1 - 2018/4/1

N2 - Grootfonteinite, Pb 3O(CO 3) 2, is a new Pb oxycarbonate found in a mineralogically complex, banded assemblage from the Mn(-Fe) oxide ore unit of the Kombat mine. Grootfonteinite is named after the locality in the Grootfontein district. The mineral forms platy grains up to 1 mm across and up to 0.2 mm thick included in and intergrown with massive cerussite. Grootfonteinite is colourless, with white streak and adamantine lustre. It is brittle with perfect cleavage on (0 0 1). The density calculated using the empirical formula H 0.345Na 0.275Ca 0.045Pb 2.645C 2O7 is 6.856 g · cm −3.The strongest five reflections in the X-ray powder-diffraction pattern [(d in Å)-(Intensity)-(hkl)] are: 4.586-25-0 1 0, 3.244-100-0 1 3, 2.652-30-1 1 0, 2.294-21-0 2 0, 2.053-39-0 2 3. Grootfonteinite crystallizes in space group P63/mmc (No. 194), a = 5.303(1), c = 13.770(3) Å, V = 335.3(1) Å3, Z = 2. The crystal structure of grootfonteinite is formed by layered blocks which consist of sheets with composition [PbCO3] and (ideally) [PbO], the stacking of which can be described as …-[PbCO 3]-[PbO]-[PbCO 3]-… The composition of the resulting electroneutral 2D block is {[Pb 2(CO 3) 2][(Pb 0.7Na 0.3)(O 0.7(OH) 0.3)]} 0. The stereochemically active 6s2 lone electron pairs of the two Pb atoms are located in between the blocks, resembling the classical case of the structure of litharge. Grootfonteinite is structurally related to hydrocerussite, abellaite, and plumbonacrite. A characteristic structural feature of all these minerals is the presence of [PbCO 3] 0 sheets in the upper and lower parts of invariably electroneutral 2D blocks, the middle part being variable. The topology of 2D blocks in the crystal structure of grootfonteinite can be considered as intermediate between those of abellaite and hydrocerussite. These three minerals can be considered to form a merotype family. Other members of this family can be hypothesized which differ in the nature of the interleaved sheets.

AB - Grootfonteinite, Pb 3O(CO 3) 2, is a new Pb oxycarbonate found in a mineralogically complex, banded assemblage from the Mn(-Fe) oxide ore unit of the Kombat mine. Grootfonteinite is named after the locality in the Grootfontein district. The mineral forms platy grains up to 1 mm across and up to 0.2 mm thick included in and intergrown with massive cerussite. Grootfonteinite is colourless, with white streak and adamantine lustre. It is brittle with perfect cleavage on (0 0 1). The density calculated using the empirical formula H 0.345Na 0.275Ca 0.045Pb 2.645C 2O7 is 6.856 g · cm −3.The strongest five reflections in the X-ray powder-diffraction pattern [(d in Å)-(Intensity)-(hkl)] are: 4.586-25-0 1 0, 3.244-100-0 1 3, 2.652-30-1 1 0, 2.294-21-0 2 0, 2.053-39-0 2 3. Grootfonteinite crystallizes in space group P63/mmc (No. 194), a = 5.303(1), c = 13.770(3) Å, V = 335.3(1) Å3, Z = 2. The crystal structure of grootfonteinite is formed by layered blocks which consist of sheets with composition [PbCO3] and (ideally) [PbO], the stacking of which can be described as …-[PbCO 3]-[PbO]-[PbCO 3]-… The composition of the resulting electroneutral 2D block is {[Pb 2(CO 3) 2][(Pb 0.7Na 0.3)(O 0.7(OH) 0.3)]} 0. The stereochemically active 6s2 lone electron pairs of the two Pb atoms are located in between the blocks, resembling the classical case of the structure of litharge. Grootfonteinite is structurally related to hydrocerussite, abellaite, and plumbonacrite. A characteristic structural feature of all these minerals is the presence of [PbCO 3] 0 sheets in the upper and lower parts of invariably electroneutral 2D blocks, the middle part being variable. The topology of 2D blocks in the crystal structure of grootfonteinite can be considered as intermediate between those of abellaite and hydrocerussite. These three minerals can be considered to form a merotype family. Other members of this family can be hypothesized which differ in the nature of the interleaved sheets.

KW - Abellaite

KW - Carbonate

KW - Grootfonteinite

KW - Hydrocerussite

KW - Kombat mine

KW - Layered structure

KW - Lead

KW - New mineral

KW - hydrocerussite

KW - GRECO-ROMAN PERIOD

KW - lead

KW - CRYSTAL-CHEMISTRY

KW - new mineral

KW - NAPB2(CO3)(2)(OH)

KW - BASIC LEAD CARBONATES

KW - grootfonteinite

KW - layered structure

KW - abellaite

KW - carbonate

KW - SILICATE

UR - http://www.scopus.com/inward/record.url?scp=85045384418&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/grootfonteinite-pb-3-o-co-3-2-new-mineral-species-kombat-mine-namibia-merotypically-related-hydrocer

U2 - 10.1127/ejm/2018/0030-2723

DO - 10.1127/ejm/2018/0030-2723

M3 - Article

VL - 30

SP - 367

EP - 373

JO - European Journal of Mineralogy

JF - European Journal of Mineralogy

SN - 0935-1221

IS - 2

ER -