Canaphite

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Canaphite
General and classification
other names

α-Calcium Disodium Diphosphate Tetrahydrate, IMA1983-067

chemical formula CaNa 2 P 2 O 7 • 4H 2 O
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates
System no. to Strunz
and to Dana 		8.FC.10
05/40/11/01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic; m
Space group Pc (No. 7)Template: room group / 7
Lattice parameters a  = 5.673 (4)  Å ; b  = 8.48 (1) Å; c  = 10.529 (5) Å
α  = 90 °; β  = 106.13 (6) °; γ  = 90 °
Formula units Z  = 2
Frequent crystal faces {010}, {001}, {100}
Physical Properties
Mohs hardness 2
Density (g / cm 3 ) 2.24 (measured); 2.08 (calculated)
Cleavage perfect after {010}
colour colorless
Line color White
transparency transparent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.496 (2)
n β  = 1.504 (2)
n γ  = 1.506 (4)
Birefringence δ = 0.01
Optical character biaxial negative
Axis angle 2V = 52 (5) °
Pleochroism not observed

The mineral canaphite is a very rare, water-containing diphosphate with the chemical composition CaNa 2 P 2 O 7 · 4H 2 O. It crystallizes with monoclinic symmetry and forms colorless, needle-like crystals a few mm in length.

Canaphite is only known from a few localities worldwide. Type locality is a basalt quarry owned by Great Notch in Little Falls Township , New Jersey , USA. Canaphite is formed at very low temperatures in the presence of an aqueous solution containing calcium and sodium .

Etymology and history

In the late 1970s, a research group at Mount Sinai Hospital in Toronto , Canada examined the calcium-phosphate deposits responsible for the symptoms of pseudogout , a rheumatic disease that predominantly affects larger joints like the knee . They also synthesized calcium disodium diphosphate tetrahydrate in three modifications and clarified the structure of these diphosphates .

Among the numerous naturally occurring phosphates, not a single polyphosphate was known at this time and it was believed that polyphosphates cannot form under geologically relevant conditions. In 1983 K. Byrappa experimentally specified this very general rule with the result that condensed phosphates are only stable up to a water pressure of ≈ 6 bar.

Donald R. Peacor and colleagues discovered a natural calcium - sodium - phosphate on a handpiece from the collection of Leo Neal Yedlin, who died in 1977 , which they initially described as a simple phosphate with the formula CaNa 2 H 2 (PO 4 ) 2 · 3H 2 O . They named canaphite after its composition of calcium, sodium and phosphorus. In 1983 it was recognized as a new mineral by the International Mineralogical Association (IMA) with the number IMA 1983-067 . The publication dragged on for another 2 years. The exact location was not known and there were doubts about the natural origin of the mineral. It then took another 3 years until these doubts could be dispelled with the help of the collector Sidney Sterris, who had already collected the samples in 1966. A structural study by Roland C. Rouse and co-workers revealed that canaphite is structurally identical to the synthetic α-calcium disodium diphosphate tetrahydrate that had been investigated at the Mount Sinai Hospital in Toronto.

Canaphite is the first mineral with a pyrophosphate anion. Since then (February 2020) only 3 other polyphosphate minerals have been recognized by the IMA: Wooldridgeit , Kanonerovit and Hylbrownit .

classification

Since the canaphite was only recognized as an independent mineral in 1983, it is not yet listed in the 8th edition of the Strunz mineral classification, which has been outdated since 1977 . Only in the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , was the mineral given the system and mineral number. VII / C.35-10 . In the "Lapis system" this corresponds to the class of "phosphates, arsenates and vanadates" and there the section " Hydrous phosphates, without foreign anions ", where canaphite together with Wooldridgeit form the group " Hydrous diphosphates [P 2 O 7 ] 4- "Forms (as of 2018).

The 9th edition of Strunz's mineral systematics, valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, classifies canaphite in the section "Polyphosphates, Polyarsenates, [4] -Polyvanadates". This is further subdivided according to OH and H 2 O content, so that the mineral can be found in the sub-section “Diphosphates etc. with only H 2 O”, where it is the only member of the unnamed group 8.FC. 10 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns canaphite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here he is to be found as the only member of the unnamed group May 40, 2011 within the sub-section “Water-containing phosphates etc., with various formulas”.


Crystal structure

Canaphite structure: bisphosphate anion, view along the a-axis. Left: Atoms, phosphorus (violet), oxygen (blue) Right: coordination polyhedron
Canaphite structure: Ca and Na environment, view along the b axis. Left: Calcium (red) surrounded by oxygen (blue) and water (turquoise) Right: Sodium (gray) surrounded by oxygen (blue) and water (turquoise)
Canaphite structure: linkage of the coordination polyhedra, view along the b-axis. Left: Layer of corner-linked phosphate tetrahedra (violet) and calcium octahedron (orange) Right: Chains of edge-linked sodium octahedra

Canaphite crystallizes with monoclinic symmetry of the space group Pc (space group no. 7) and 2 formula units per unit cell . The natural canaphite from the type locality has the lattice parameters a  = 5.673 (4)  Å , b  = 8.48 (1) Å, c  = 10.529 (5) Å and β = 106.13 (6) °. Template: room group / 7

Phosphorus (P 5+ ) occupies two tetrahedral positions surrounded by 4 oxygen ions. The two tetrahedra are connected by a common oxygen ion at one corner to form a P 2 O 7 group.

Calcium (Ca 2+ ) is octahedral surrounded by five oxygen and one water molecule, sodium (Na + ) also octahedral by 3 oxygen and 3 water molecules.

The P 2 O 7 groups are linked via the Ca octahedron via corners - common oxygen - to form chains along the c-axis. These chains are connected via another tetrahedral-octahedral corner in the a-direction to form a calcium phosphate layer.

The Na octahedra are linked by common edges to form chains along the a-axis. These chains connect the calcium phosphate layers in the direction of the b-axis.


Education and Locations

Canaphite crystallizes at low temperatures from aqueous solutions that contain no other metal ions besides alkali and alkaline earth ions.

In its type locality , the basalt quarry of the Great Notch Company in Little Falls Township , New Jersey , USA, canaphite is found in cavities on stilbite and is the last mineral to crystallize there.

Another occurrence is limestone and dolomite from the Moscow region . After dissolving the lime with acetic acid , canaphite was found in the insoluble residues along with quartz , chalcedony , sanidine , zircon , apatite , pyrite , goethite and manganese oxides. It is believed that canaphite was formed here during the diagenesis of the limestone.

See also

Web links

Individual evidence

  1. ↑ a b c d e f g P.-T. Cheng and KPH Pritzker: α-Calcium Disodium Pyrophosphate Tetrahydrate . In: Acta Crystallographica . B36, 1980, p. 921-924 ( researchgate.net [PDF; 345 kB ; accessed on February 10, 2020]).
  2. ↑ a b c d e f g h i Roland C. Rouse, Donald R. Peacor, Robert L. Freed: Pyrophosphate groups in the structure of canaphite, CaNa 2 P 2 O 7 · 4H 2 O: The first occurrence of a condensed phosphate as a mineral . In: American Mineralogist . tape 73 , 1988, pp. 168–171 ( rruff.info [PDF; 448 kB ; accessed on February 10, 2020]).
  3. ↑ a b c d e f g h i j k l m n o p DR Peacor, PJ Dunn, WB Simmons, FJ Wicks: Canaphite, a new sodium calcium phosphate hydrate from Paterson Area, New Jersey (abstr.) . In: American Mineralogist . tape 71 , 1986, pp. 1543–1544 ( minsocam.org [PDF; 837 kB ; accessed on March 3, 2020]).
  4. ↑ Find location list for canaphite at the Mineralienatlas and at Mindat
  5. ↑ K. Byrappa: The possible reasons for the absence of condensed phosphates in nature . In: Physics and Chemistry of Minerals . tape 10 , 1983, p. 94-95 , doi : 10.1007 / BF00309591 .
  6. ↑ Stefan Weiß: The large 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 .
  7. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1816 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed March 8, 2020 .
  8. ↑ Yu. V. Yashunsky, OS Berezner, KA Scripko, LD Semenova, AN Filaretova: Authigenic minerals in the Moscow region carbonate rocks: A case study of the exhibition in the scientific Library of the MSU faculty of geology . In: Жизнь Земли . tape 40 , no. 1 , 2018, p. 43–51 ( cyberleninka.ru [PDF; 3.5 MB ; accessed on March 3, 2020]).