Cuspidine

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Cuspidine
General and classification
other names

Custerite

chemical formula
  • Ca 8 (Si 2 O 7 ) 2 F 4
  • Ca 8 [F 4 | (Si 2 O 7 ) 2 ]
  • Ca 4 [(F, OH) 2 | Si 2 O 7 ]
Mineral class
(and possibly department) 		Silicates and Germanates - group silicates
System no. to Strunz
and to Dana 		9.BE.17 ( 8th edition : VIII / B.06)
56.02.04.03
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / a (No. 14, position 3)Template: room group / 14.3
Lattice parameters a  = 10.91  Å ; b  = 10.52 Å; c  = 7.52 Å
β  = 109.3 °
Formula units Z  = 2
Twinning simple, lamellar and polysynthetic according to {100}
Physical Properties
Mohs hardness 5 to 6
Density (g / cm 3 ) measured: 2.85 to 2.96; calculated: 2.978
Cleavage very good after {001}, clearly after {110}
Break ; Tenacity uneven; brittle
colour colorless, white, pale pink to rose red, chocolate brown
Line color White
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.586 to 1.594
n β  = 1.589 to 1.596
n γ  = 1.598 to 1.606
Birefringence δ = 0.012
Optical character biaxial positive
Axis angle 2V = 59 ° to 71 ° (measured), 58 ° to 66 ° (calculated)

Cuspidin is a rarely occurring minerals from the mineral class of "silicates and germanates" with the chemical composition Ca 8 [F 4 | (Si 2 O 7 ) 2 ] and thus chemically seen a calcium - silicate with additional fluoride ion .

Cuspidin crystallizes in the monoclinic crystal system and typically develops spearhead-shaped crystals as well as simple, lamellar or polysynthetic twins of a few millimeters in size with a glass-like sheen on the surfaces. In its pure form, cuspidin is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline training, it can also be translucent white and, due to foreign admixtures, take on a pale pink to pinkish-red or chocolate-brown color. His line color , however, is always white.

Etymology and history

Cuspidin was first discovered in mineral samples from the Monte Somma volcano near Naples in Italy , which at the time had already been kept in the Museum of Mineralogy in Naples for several years. It was first described in 1876 by the Italian geologist, mineralogist and volcanologist Arcangelo Scacchi , who named the mineral after the characteristic, spear-shaped crystal form from the Latin word [cuspis] for “spear”, “spear”, “point” or “sting” (after Scacchi also called lancet, Italian: lancetta ).

In 1914, Joseph Bertram Umpleby (1883-1967), Waldemar Theodore Schaller and Esper S. Larsen described a new, contact metamorphic mineral that was discovered in a contact zone about 3.5 miles southwest of Mackay in Custer County, Idaho . 1947 presented Cecil Edgar Tilley and HCG Vincent in their investigations over Cuspidine from the kontaktmetamorphen dolomite - skarns at Broadford on the Scottish island of Skye firmly (Isle of Skye) that Custerit is identical to the already known Cuspidin. The name Custerit was therefore discredited and is now considered a synonym for Cuspidin.

classification

Already in the outdated 8th edition of the mineral classification according to Strunz , the cuspidin belonged to the mineral class of "silicates and germanates" and there to the department of "sorosilicates" (with non-tetrahedral anions ), where together with Tilleyit it belongs to the "Cuspidin-Tilleyit group" the system no. VIII / B.06 and the other member Rustumit . The minerals suolunite (also solanite ) and foshallasite (discredited 2006) are assigned to the group in the appendix .

In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the system and mineral number. VIII / C.09-10 . In the "Lapis system" this also corresponds to the section "Group silicates (sorosilicates)", where cuspidin forms an independent but unnamed group together with Aklimait , Fukalith , Jaffeit , Killalait , Rusinovit , Suolunit and Tilleyit.

The valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009 [[Systematics of Minerals according to Strunz (9th edition) #E. Si2O7 groups with additional anions; Cations in octahedral [6] and greater coordination | 9. Edition of the Strunz'schen mineral systematics]] also assigns the cuspidin to the department of "group silicates (sorosilicates)". However, this is further subdivided according to the structure of the silicate groups as well as the possible presence of additional anions and the coordination of the cations , so that the mineral according to its composition and structure is classified in the subsection “Si 2 O 7 groups with additional anions; Cations in octahedral [6] and greater coordination ”can be found, where it is named after the“ cuspid group ”with the system no. 9.BE.17 and the other members Baghdadite , Burpalite , Hiortdahlite , Janhaugite , Låvenite , Marianoite , Niocalite , Normandite and Wöhlerite .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns cuspidin to the class of "silicates and germanates", but there in the more finely subdivided division of "group silicates: Si 2 O 7 groups and O, OH, F and H 2 O “a. Here he is with Baghdadit, Burpalit, Låvenit, Wöhlerit, Niocalit, Hiortdahlit, Rosenbuschite , Hainit , Janhaugit, jennite , Komarovit , Natrokomarovit , Suolunit, Mongolit , Kristiansenit , Kochit , Marianoit in the " Cuspidin-Wöhlerit group " with the system -No. 56.02.04 within the subsection “Group silicates: Si 2 O 7 groups and O, OH, F and H 2 O with cations in [4] and / or> [4] coordination”.

Crystal structure

Cuspidin crystallizes monoclinically in the space group P 2 1 / a (space group no. 14, position 3) with the lattice parameters a  = 10.91  Å ; b  = 10.52 Å; c  = 7.52 Å and β = 109.3 ° and two formula units per unit cell . Template: room group / 14.3

Education and Locations

At its type locality on the Monte Somma volcano in Italy, cuspidine was found in its carbonate ejecta . But it can also arise through contact metamorphosis in limestone , such as in Franklin (New Jersey) or in Melilith - Skarn such as on Mount Dupezeh near Qala Diza ( Qeladze , قلعة دزة) in the Gouvernement as-Sulaimaniyya in the autonomous region of Kurdistan in northern Iraq . Depending on the location, augite , biotite , calcite , diopside , grossular , hornblende , magnetite , monticellite , perovskite , phlogopite , spinel and wollastonite appear as accompanying minerals .

As a rare mineral formation, cuspidin could only be detected in a few places worldwide, with around 80 sites being documented so far. In addition to its type locality Monte Somma, the mineral occurred in Italy, among other things, in the nearby San Vito quarry near Ercolano in Campania; at Ariccia , Monte Sant'Angelo , Rocca di Papa and at Lake Vico in Latium ( Lazio ); in the Case Collina pumice quarry near Pitigliano in Tuscany as well as in the leucite - kalsilite - melilithites near Colle Fabbri near Spoleto and in the quarry (Cava) Vispi at the volcano Pian di Celle near the municipality of San Venanzo in the Umbria region.

In Germany Cuspidin found so far in the quarry Caspar on Ettringer Bellerberg in Mayen-Koblenz, at Feuerberg at Hohenfels-Essingen and the Emmelberg in Udersdorf in Vulkaneifel in Rhineland-Palatinate and in mineral samples from the Absetzerhalde of the open pit Lichtenberg in the uranium - deposit near Ronneburg in Thuringia.

Other well-known sites in Europe include some slag heaps near Lapanouse in the French department of Aveyron and in the area of ​​Puntazeza near Lavrio in the Greek region of Attica , Barnavave near Carlingford ( County Louth ) and Enniscrone (also Inishcrone , County Sligo ) in Ireland , Flekkeren near Skien in Norway, the spoil heaps of the Bolesław mine near Przygórze (Lower Silesia) and the heaps near Bytom - Bobrek and Siemianowice Śląskie - Dąbrowka Wielka (Silesia) in Poland, near Racoş , in a basalt quarry near Odorheiu Secuiesc and near Brad and on the mountain Cornet near Hunedoara in Romania, the Rosice - Oslavany coal area in Okres Brno-venkov in the Czech Republic and on the Ardnamurchan peninsula and the islands of Muck and Skye in Scotland in the United Kingdom.

Worldwide there are still individual sites in Australia, Brazil, China, Canada, the Congo, Iraq, Israel, Japan, Namibia, New Zealand, Palestine, Russia, South Africa, South Ossetia, Tanzania, Turkey, Ukraine and the United States of America known.

See also

literature

  • A. Scacchi: Della cuspidina e del neocrisolito, nuovi minerali vesuviani . In: Rendiconto dell'Accademia delle Scienze Fisiche e Matematiche . tape 15 , 1876, p. 208–209 (Italian, rruff.info [PDF; 213 kB ; accessed on May 13, 2019]).
  • S. Saburi, A. Kawahara, C. Henmi, I. Kusachi, K. Kihara: The refinement of the crystal structure of cuspidine . In: Mineralogical Journal . tape 8 , 1977, pp. 286–298 (English, rruff.info [PDF; 696 kB ; accessed on May 13, 2019]).
  • AV Valkenburg, GF Rynders: Synthetic cuspidine . In: American Mineralogist . tape 43 , 1958, pp. 1195–1202 (English, rruff.info [PDF; 485 kB ; accessed on May 13, 2019]).

Web links

Individual evidence

  1. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  692 (first edition: 1891).
  2. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2019. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2019, accessed May 13, 2019 .
  3. ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  575 (English).
  4. ↑ a b c d e Stefan Weiss: The great Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  5. ^ A b Karl Hugo Strunz , Christel Tennyson : Mineralogical tables . 8th edition. Academic publishing company Geest & Portig KG, Leipzig 1982, p.  391 .
  6. ↑ David Barthelmy: Cuspidine Mineral Data. In: webmineral.com. Retrieved May 29, 2019 .
  7. ↑ a b c d e f g h Cuspidine . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 71  kB ; accessed on May 28, 2019]).
  8. ↑ a b c d e Cuspidine. In: mindat.org. Hudson Institute of Mineralogy, accessed May 28, 2019 .
  9. ↑ Ulrico Hoepli: Arcangelo Scacchi (obituary with bibliography) . In: Giornale di mineralogia, cristallografia e petrografia . tape V , 1894, p. 1–22 , p. 20: Della cuspidina e del neocrisolito, nuovi minerali vesuviani  - Internet Archive (Italian, archive.org  - Internet Archive [accessed May 13, 2019]).
  10. ↑ cuspis. In: langenscheidt.com. Langenscheidt dictionary, accessed on May 14, 2019 .
  11. ↑ A. Scacchi: Della cuspidina e del neocrisolito, nuovi minerali Vesuviani . In: Rendiconto dell'Accademia delle Scienze Fisiche e Matematiche . tape 15 , 1876, p. 208–209 (Italian, rruff.info [PDF; 213 kB ; accessed on May 13, 2019]).
  12. ↑ JB Umpleby , WT Schaller , ES Larsen : XXIV. Custerite, a new contact metamorphic mineral . In: Journal of Crystallography - Crystalline Materials . tape  53 , 1914, pp. 321-331 , doi : 10.1524 / zkri.1914.53.1.321 ( degruyter.com [PDF; 577 kB ; accessed on June 3, 2019] accessed via De Gruyter Online).
  13. ^ CE Tilley, HCG Vincent: Cuspidine from dolomite contact skarns, Broadford, Skye . In: Mineralogical Magazine . tape 28 , 1947, pp. 90–95 (English, rruff.info [PDF; 1.5 MB ; accessed on June 3, 2019]).
  14. ↑ Ernst AJ Burke: A Mass Discreditation of GQN Minerals . In: The Canadian Mineralogist . tape 44 , 2006, pp. 1557–1560 , Foshallasite or Foshallassite = zeophyllite (English, rruff.info [PDF; 116 kB ; accessed on May 13, 2019]).
  15. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed May 13, 2019 .
  16. ↑ Marco E. Ciriotti, Lorenza Fascio, Marco Pasero: Italian Type Minerals . 1st edition. Edizioni Plus - Università di Pisa, Pisa 2009, ISBN 978-88-8492-592-3 , p. 96 .
  17. ↑ Localities for Cuspidine. In: mindat.org. Hudson Institute of Mineralogy, accessed May 28, 2019 .
  18. ↑ List of locations for cuspidin in the Mineralienatlas and Mindat