Podlesnoit

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Podlesnoit
General and classification
other names

IMA 2006-033

chemical formula
  • BaCa 2 (CO 3 ) 2 F 2
  • Ca 2 Ba (CO 3 ) 2 F 2
Mineral class
(and possibly department) 		Carbonates and nitrates
System no. to Strunz
and to Dana 		5.BC.15 ( 8th edition : Vb / B.04 (?))
16a.02.05.01
Similar minerals Thomsonite
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Cmcm (No. 63)Template: room group / 63
Lattice parameters a  = 12.501  Å ; b  = 5.857 Å; c  = 9.433 Å
Formula units Z  = 4
Frequent crystal faces {100}, {110}, {2l0} and {001}
Twinning none, but widespread parallel adhesions
Physical Properties
Mohs hardness 3.5 to 4
Density (g / cm 3 ) 3.62 (measured); 3.63 (calculated)
Cleavage no
Break ; Tenacity clamshell; brittle
colour colorless-water-clear (crystals); snow white (aggregates); Colorless in transmitted light
Line color White
transparency transparent (crystals) or translucent (aggregates)
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.500
n β  = 1.612
n γ  = 1.614
Birefringence δ = 0.114
Optical character biaxial negative
Axis angle 2V = 10 ° (measured); 14 ° (calculated)
Pleochroism unavailable
Other properties
Chemical behavior Slow dissolution in dilute and concentrated HCl at room temperature
Special features strong pink-orange fluorescence in short-wave UV light (crystals); weak bluish purple fluorescence in short-wave UV light (aggregates)

Podlesnoite is a very rarely occurring mineral from the mineral class of " carbonates and nitrates ". It crystallizes in the orthorhombic crystal system with the idealized chemical composition BaCa 2 (CO 3 ) 2 F 2 and is therefore chemically a barium - calcium - carbonate with additional fluorine ions.

Podlesnoite mainly forms perfectly formed prismatic, [001] elongated crystals up to 1 mm in size, which come together in groups of 2 cm in diameter. Individual crystals are rare. In addition, it can be found in the form of radial, spherulitic aggregates with a maximum diameter of 5 mm, which consist of thin needle-like or fibrous individuals.

The type locality of the Podlesnoite is the "Apatite Mine Kirow" named after Sergei Mironowitsch Kirow ( coordinates of the apatite mine Kirow ), which is also called "Kirovskii Apatite Mine", "Kirovsky Mine", "Kirovskii Mine" or "Kirov Mine" ( Russian Кировский руднкий ) known and is located south of the mountain Kukiswumtschorr (Kukisvumchorr) in the southern part of the Chibinen massif, Murmansk Oblast , Kola Peninsula , Russia .

Etymology and history

In the last days of January 2006, a mining operation was carried out in the apatite mine in Kirov, in which the demolition master Aleksandr Semenovich Podlesnyi found a lenticular, approx. 3 m long hydrothermal body at the beginning of February 2006, which mainly consisted of natrolite and contained cavernous areas with an unknown mineral. Already after the first chemical and X-ray diffractometric examinations it turned out to be a new calcium-barium-fluorocarbonate. After intensive further investigations, the mineral was presented to the International Mineralogical Association (IMA), which recognized it as a new mineral in 2006 under the provisional designation IMA 2006-033.

In 2008, the first scientific description of this mineral was made by a team of Russian scientists with Igor V. Pekov, Natalia V. Zubkova, Nikita V. Chukanov, and Dmitriy Yu. Pushcharovsky, Natalia N. Kononkova and Aleksandr E. Zadov in the American science magazine The Mineralogical Record as podlesnoite ( Russian Подлесноит , English podlesnoite ). They named the mineral after the finder, the Russian amateur mineralogist and collector Aleksandr Semenovich Podlesnyi ( Russian Александр Семенович Подлесный ) (1948-2010). Podlesnyi was one of the best experts on the minerals of the "Kirov apatite mine". His more than 25 years of collaboration with professional mineralogists led to the first description of numerous new minerals. Material from his own collections forms the holotype of eleven minerals ( Tuliokit , Kukisvumit , Sitinakit , Belovit- (La) , Labuntsovit-Fe , Lemmleinit-Ba , Kukharenkoit- (La) , Shirokshinite , Middendorfite , Armbrusterite and Podlesnoite) as well as the cotype of others four new minerals ( Kukharenkoite- (Ce) , Tsepinit-K , Neskevaarait-Fe, and Potassicarfvedsonite ) - which is likely a modern record for the number of new minerals described based on a single collector's own findings .

The type material for podlesnoite is kept under catalog number 3460/1 in the systematic collection of the Mineralogical Museum " Alexander Evgenjewitsch Fersman " of the Russian Academy of Sciences in Moscow .

classification

The 8th edition of the mineral classification according to Strunz , which is now outdated, but still in use in some cases, does not yet list the podlesnoite. It would belong to the mineral class of "carbonates, nitrates and borates" and there probably to the general department of "anhydrous carbonates with foreign anions ", where it would belong together with the bastnesites and hydroxylbastnesites and the other members cebaite (Ce) , cordylite (Ce ) , Horváthit- (Y) , Huanghoit- (Ce) , Kozoit- (La) , Kozoit- (Nd) , Kukharenkoit- (Ce) , Kukharenkoit- (La) , Lukechangit- (Ce) , Micheelsenite , Mineevit- (Y ) , Parisit- (Ce) , Parisit- (Nd) , Qaqarssukit- (Ce) , Reederit- (Y) , Röntgenit- (Ce) , Synchisit- (Ce) , Synchisit- (Nd) , Synchisit- (Y) and Zhonghuacerit- (Ce) the "Bastnäsite-Hydrocerussit-Gruppe" with the system no. Vb / B.04 would have formed.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns the podlesnoite to the newly defined class of "carbonates and nitrates" (the borates form a separate class here), but also in the department of “carbonates with additional anions; without H 2 O “. This is further subdivided according to the predominant cations in the compound , so that the mineral can be found according to its composition in the sub-section “With alkaline earth cations”, where it is the only member of the unnamed group 5.BC.15 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the podlesnoite, like the outdated Strunz system, to the common class of “carbonates, nitrates and borates” and there to the “carbonates - hydroxyl or halogen” class. Here he is the only member of the unnamed group 16a.02.05 within the subsection “Carbonates - Hydroxyl or Halogen with (AB) 3+ (XO 3 ) 2 Z q ”.

Chemism

Mean values from eight microprobe analyzes on podlesnoite from the type locality yielded 0.11% Na 2 O; 0.05% K 2 O; 29.02% CaO; 0.13% SrO; 40.77% BaO; 0.07% MnO; 0.25% FeO; 22.9% CO 2 ; 9.95% F (−O = F 2 4.19, total 99.06%). The contents of Mg , Pb , Y , lanthanoids , Al , Si and Cl are below the detection limit . IR analyzes showed that no H 2 O is present. From the microprobe analyzes, the empirical formula Ba 1.02 (Ca 1.98 Fe 0.01 Na 0.01 Sr 0.005 ) Σ = 2.005 C 1.99 O 6 F 2.00 was calculated on the basis of six oxygen atoms Can be idealized to BaCa 2 (CO 3 ) 2 F 2 and contents of 29.87% CaO; 40.83% BaO; 23.44% CO 2 and 10.12% F (−O = F 2 4.26, total 100.00%) required.

The element combination Ba – Ca – C – O – F is unique among the currently known minerals; so there are no minerals with a chemical composition with the same chemical elements as podlesnoite. Brenkit , Ca 2 (CO 3 ) F 2 , are chemically similar ; Rouvilleit , Na 3 (Ca, Mn, Fe) 2 (CO 3 ) 3 F; Aravaite , Ba 2 Ca 18 (SiO 4 ) 6 (PO 4 ) 3 (CO 3 ) F 3 O; Cordylite- (Ce) , NaBaCe 2 (CO 3 ) 4 F; Cordylite- (La) , (Na, Ca) Ba (La, Ce, Sr) 2 (CO 3 ) 4 F; Daqingshanite- (Ce) , (Sr, Ca, Ba) 3 (Ce, La) (CO 3 ) 3-x (PO 4 ) (OH, F) 2x ; Hanjiangite , Ba 2 CaV 3+ Al (H 2 AlSi 3 O 12 ) (CO 3 ) 2 F; Stracherite , BaCa 6 (SiO 4 ) 2 [(PO 4 ) (CO 3 )] 2 F; as well as the not yet described cordylite-like mineral Ca □ Ba 2 Ce 4 [CO 3 ] 8 F 2 . Podlesnoite is only the second mineral after Brenkite, which only contains alkaline earth metals as cations.

Crystal structure

Podlesnoite crystallizes in the orthorhombic crystal system in the space group Cmcm (space group no. 63) with the lattice parameters a = 12.501  Å , b = 5.857 Å and c = 9.433 Å as well as four formula units per unit cell . Template: room group / 63

The basis of the crystal structure of the Podlesnoits is a dense, honeycomb-type structure containing [001] extended columns of CaO in the direction of the c axis 6 F 2 - polyhedron , which are linked together by common edges, is constructed. In the center of the polyhedron is an eight-fold coordinated Ca atom. The (CO 3 ) groups and large barium atoms that are coplanar with the ac plane are located in the cavities of this framework . Ten-coordinate Ba atoms are in the center of the (BaO 6 F 4 ) polyhedra, while fluorine atoms are in the center of the (FCa 2 Ba 2 ) tetrahedron .

Crystal structure of podlesnoite

  • spatial representation in the standard crystallographic orientation

  • looking parallel to the a-axis

  • looking parallel to the b-axis

  • looking parallel to the c-axis

Color legend: __ Ba     __ Ca     __ C     __ O     __ F

The structure of the podlesnoite is distantly related to that of the representatives of the aragonite group and can be regarded as a derivative of the aragonite-type structure. The transition from the aragonite to the podlesnoite structure can be seen as an ordered substitution of ⅓ of the Ca cations by larger Ba cations and of ⅓ of the (CO 3 ) groups by pairs of F atoms according to the equation [3Ca] + [3 (CO 3 )] → [2Ca + Ba] + [2 (CO 3 ) + 2F]. This transformation causes a change in the cation / anion ratio from 1: 1 in aragonite to 3: 4 in podlesnoite and leads to significant structural changes. As a result, the minerals of the aragonite group differ from the podlesnoite in symmetry, the dimensions of the unit cell and the X-ray diffraction pattern.

properties

morphology

Podlesnoite is found within cavities in the form of incrustations on natrolite, ilmenite , biotite and barytocalcite . The mineral occurs in two different varieties, which differ significantly in terms of their morphology, color and fluorescence properties, but are chemically identical and have the same optical properties as well as the same X-ray diffraction pattern and IR spectrum. Variety I forms perfectly crystallized prismatic, [001] elongated crystals up to 1 × 1 × 4 mm in size, which are typically combined into groups of up to 1.5 × 2 mm in size. Isolated single crystals are rare. The shape that determines the costume is the pinacoid {100}, other common surface shapes are {110}, {210} and {001}. The forms {101}, {112} and {313} only appear subordinate, the forms {111} and {021} only rarely. The costume of large crystals consists of the dominant forms {100}, {001}, {110} and {210}, while {101}, {112} and {313} are only subordinate (see "Costume 1" in crystal drawings opposite). Such crystals with the surface shapes mentioned can be very similar to thomsonite crystals. Smaller crystals have more complicated combinations of the surface shapes mentioned, in some cases with well-developed dipyramids such as {101} and {313} (see “Costume 2–4” in the crystal drawings opposite). The shapes {110} and {210} are typically parallel striped [001], with some crystals on the base pinacoid {001} showing a striping parallel to the b-axis [010]. Twins do not exist, whereas parallel adhesions are common.

  • Costume and habitus of podlesnoite crystals (the same colors mean the same surface shapes)

  • 1. Podlesnoit crystal costume 1

  • 2. Podlesnoit crystal costume 2

  • 3. Podlesnoit crystal costume 3

  • 4. Podlesnoit crystal costume 4

Variety II, on the other hand, is found in the form of dense spherulites with a diameter of up to 5 mm, which have a radial structure of needle-like to fibrous individuals elongated according to [010]. The surface of these spherical aggregates is mostly completely covered with overgrowths of oriented crystals of variety I, which indicates that variety I was formed later than variety II and is consequently younger than this. Such combined and oriented aggregate-crystal intergrowths reach a diameter of 5 mm. The terminations of these fibers / needles act as a seed for crystals of variety I. In this way, the longitudinal axis of the [001] stretched crystals of variety I is always exactly at right angles to the longitudinal axis of the underlying fibers / needles of variety II, i.e. tangential to the surface the spherulites, aligned. This auto-epitaxial intergrowth of the Podlesnoite varieties I and II can be compared with the oriented intergrowth of quartz and chalcedony , as described by Georgii Glebowitsch Lemmlein . Here “normal” rhombohedral-prismatic quartz crystals lie auto-epitaxially on spherical chalcedony aggregates, which consist of [11 2 0] or [10 1 0] stretched quartz fibers.

physical and chemical properties

Podlesnoite crystals are colorless, water-clear, while the aggregates are snow-white. Their line color , however, is always white. The surfaces of the transparent crystals show a characteristic glass-like sheen . Aggregates are translucent. According to this glass gloss, podlesnoite has a medium refraction (n α  = 1.500; n β  = 1.612; n γ  = 1.614) and a high birefringence (δ = 0.114). In transmitted light, the mineral is colorless and has no pleochroism .

Podlesnoite shows no cleavage , but because of its brittleness it breaks like quartz , whereby the fracture surfaces are shell-shaped. The mineral has a Mohs hardness of 3.5 to 4 and is therefore one of the medium-hard minerals that can be easily scratched with a pocket knife, just as easily as the reference mineral fluorite (hardness 4). The measured density for podlesnoite is 3.62 g / cm³, the calculated density is 3.63 g / cm³.

Podlesnoite crystals show a strong pink-orange fluorescence in short-wave UV light, but do not fluoresce in long-wave UV light. The sweat-white aggregates, on the other hand, show a weak bluish-purple fluorescence in short-wave UV light and a very weak purple-blue fluorescence in long-wave UV light.

The crystals of podlesnoite slowly dissolve at room temperature in dilute and concentrated hydrochloric acid , HCl, with a very gentle bubbling. Finely ground podlesnoite powder, on the other hand, easily dissolves in both dilute and concentrated HCl with strong foaming.

Education and Locations

Podlesnoite was discovered at its type locality in a small, lenticular, 3.2 × 0.9 m large hydrothermal body, which consisted mainly of natrolite and was completely seated in urtitic rock. This urtite is a light- colored plutonic, feldspar-free rock, which belongs to the Ijolite family and consists mainly of nepheline and a maximum of 30% of mafic minerals, in this case pyroxene (aegirine diopside), titanite and fluorapatite . The hydrothermalite was separated from the surrounding urtite by a maximum 10 cm thick transition zone made of natrolithized urtite, which was rich in gray-white fibrous lorenzenite and contained masses of brown cancrinite . Podlesnoite was found in the hydrothermalite mentioned in small cavities accompanied by the paragenesis minerals mentioned below. In the entire hydrothermal body, no feldspars , nepheline , sodalite , diopside , amphibole or eudialyte and also no zirconium-containing minerals were found, which are otherwise very common in the alkali rock pegmatites of the Chibinen massif. Due to this fact and the presence of a transition zone between urtitic host rock and the natrolite body, it is assumed that it is actually a pure hydrothermalite and not a pegmatite .

Typical accompanying minerals of podlesnoite are natrolite, biotite, ilmenite, aegirine , fluorapatite , lorenzenite, barytocalcite, calcite , fluorite , astrophyllite , burbankite , lemmleinite-K and fluorapophyllite- (K), which fluoresce in a strong greenish yellow in short-wave UV light . Biotite, aegirine, ilmenite and fluoroapatite are the first minerals formed in this hydrothermal body, while natrolite and lorenzenite were formed later. Calcite, barytocalcite, podlesnoite, fluorite, astrophyllite, burbankite, lemmleinite-K and fluorapophyllite- (K) represent the last minerals formed in this hydrothermal body, which can only be found in cavities. The chemical formula of Podlesnoite, BaCa 2 (CO 3 ) 2 F 2 , can also be represented as BaCa (CO 3 ) 2  • CaF 2 . Barytocalcite, BaCa (CO 3 ) 2 , and fluorite, CaF 2 , are closely associated with podlesnoite, with barytocalcite being formed before podlesnoite and fluorite after podlesnoite. The crystallization of the podlesnoite was possibly associated with a decrease in the barium concentration in the hydrothermal solution and a corresponding increase in the fluorine concentration. While the association of barytocalcite and its polymorphic modifications alstonite and paralstonite with fluorite is known from numerous sites, podlesnoite is the first known natural barium calcium fluorocarbonate and its artificial analogue has yet to be synthesized. This is possibly an indication that the Podlesnoit field of stability is very narrow and that its formation is only possible under very limited conditions.

As an extremely rare mineral formation, the podlesnoite has so far (as of 2019) only been described by one finding point. The type locality for Podlesnoit is after Sergey Kirov called "apatite mine Kirov" (also called "Kirovskii Apatite Mine," "Kirovsky Mine", "Kirovskii Mine" or "Kirov Mine", Russian Кировский рудник ) south of the mountain Kukiswumtschorr (Kukisvumchorr) in southern part of the Chibinen massif, Murmansk Oblast , Kola Peninsula , Russia .

Sites for podlesnoite from Germany , Austria and Switzerland are therefore unknown.

use

Because of its rarity, podlesnoite is only of interest to mineral collectors.

See also

literature

  • Igor V. Pekov, Natalia V. Zubkova, Nikita V. Chukanov, Dmitriy Yu. Pushcharovsky, Natalia N. Kononkova, Aleksandr E. Zadov: Podlesnoite BaCa 2 (CO 3 ) 2 F 2  : A new mineral species from the Kirovskii Mine, Khibiny, Kola Penninsula, Russia . In: The Mineralogical Record . tape 39 , no. 2 , 2008, p. 137–148 (English, rruff.info [PDF; 8.6 MB ; accessed on February 16, 2019]).
  • Igor V. Pekov: New minerals from former Soviet Union countries, 1998-2006: new minerals approved by the IMA commission on new minerals and mineral names . In: Mineralogical Almanac . tape 11 , 2007, p. 9–51 (English, rruff.info [PDF; 3.9 MB ; accessed on February 16, 2019]).
  • Natalia V. Zubkova, Dmitriy Yu. Pushcharovsky, Igor V. Pekov, Murtazali Kh. Rabadanov: The crystal structure of podlesnoite, BaCa 2 (CO 3 ) 2 F 2 . In: Journal of Crystallography . tape 222 , no. 9 , 2007, p. 474–476 , doi : 10.1524 / zkri.2007.222.9.474 (English).

Web links

Commons : Podlesnoite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd Igor V. Pekov, Natalia V. Zubkova, Nikita V. Chukanov, Dmitriy Yu. Pushcharovsky, Natalia N. Kononkova, Aleksandr E. Zadov: Podlesnoite BaCa 2 (CO 3 ) 2 F 2  : A new mineral species from the Kirovskii Mine, Khibiny, Kola Penninsula, Russia . In: The Mineralogical Record . tape 39 , no. 2 , 2008, p. 137–148 (English, rruff.info [PDF; 8.6 MB ; accessed on February 16, 2019]).
  2. ^ IMA / CNMNC List of Mineral Names; November 2018 (PDF 1.65 MB)
  3. ↑ a b c d Podlesnoite. In: mindat.org. Hudson Institute of Mineralogy, accessed February 16, 2019 .
  4. ↑ a b Georgii Glebowitsch Lemmlein : On overgrowing of quartz on chalcedony . In: Special volume dedicated to Academician Dmitry Stepanovich Belyankin's 70th anniversary and 45 years of his scientific activity . 1st edition. Academy of Sciences Publishing, Moscow 1946, pp.  131-139 (Russian).
  5. ↑ Localities for Podlesnoite. In: mindat.org. Hudson Institute of Mineralogy, accessed February 16, 2019 .
  6. ↑ Find location list for podlesnoite at the Mineralienatlas and at Mindat (accessed on February 16, 2019)