Susannite

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Susannite
Lanarkite, Susannite, Macphersonite-359326.jpg
Lanarkite (white) and Susannite (blue) from the "Susanna Mine" near Leadhills in South Lanarkshire, Scotland (size: 4 × 3 × 2 cm)
General and classification
other names

Suzannite

chemical formula Pb 4 [(OH) 2 | (CO 3 ) 2 | SO 4 ]
Mineral class
(and possibly department) 		Carbonates and nitrates (formerly sulfates, selenates, tellurates, chromates, molybdates, wolframates)
System no. to Strunz
and to Dana 		5.BF.40 ( 8th edition : VI / B.13)
01/17/03/01
Crystallographic Data
Crystal system trigonal
Crystal class ; symbol trigonal-pyramidal; 3
Space group P 3 (No. 143)Template: room group / 143
Lattice parameters a  = 9.07  Å ; c  = 11.57 Å
Formula units Z  = 3
Physical Properties
Mohs hardness 2.5 to 3
Density (g / cm 3 ) calculated: 6.52
Cleavage completely after {0001}
colour colorless, white, light green, light yellow, brown
Line color White
transparency transparent to translucent
shine Diamond luster
Crystal optics
Axis angle 2V = 0 to 3 °
Other properties
Special features fluorescence

Susannite is a rarely occurring mineral from the mineral class of " carbonates and nitrates ". It crystallizes in the trigonal crystal system with the composition Pb 4 [(OH) 2 | (CO 3 ) 2 | SO 4 ], and is thus chemically seen a lead - double salt .

Susannite is mostly found in the form of millimeter-sized, isometric and rhombohedral crystals . In its pure form it is colorless and transparent. However, due to multiple light refraction due to lattice construction defects or multicrystalline formation, it can also appear white and, due to foreign admixtures, take on a light green, light yellow or brown color. However, the line color is always white.

Etymology and history

Susannite was first discovered in the “Susanna Mine” (also known as “Glennery Scar”, “Susanna”, “Portobello”, “Humby” or “Lead” gang) at Leadhills in Scotland in the United Kingdom.

The mineral was first mentioned in 1820 by Henry James Brooke , who analyzed the sulphato-tricarbonate of lead from Leadhills and described its shape as rhombohedral (trigonal). Wilhelm Ritter von Haidinger , on the other hand, considered the shape to be two-part and one-part (monoclinic and triclinic) and in 1845 gave the mineral the name susannite (or suzannite ) based on its type locality . Later investigations by Brooke and Miller showed, however, that two lead double salts of the same composition occur in Leadhills, of which Leadhillite is monoclinic and Susannite is trigonal (rhombohedral).

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the susannite still belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates, wolframates" and to the department of "anhydrous sulfates with foreign anions ", where it together with Grandreefit , Lanarkit , Leadhillit, Macphersonit , Olsacherit and Pseudograndreefit the independent group VI / B.13 formed.

In contrast , 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 susannite to the class of “carbonates and nitrates” and there to the category of “carbonates with additional anions; without H 2 O “. This section is further subdivided according to the type of other anions, so that the mineral can be found in the subdivision "With Cl, SO 4 , PO 4 " according to its composition , where it only forms the "leadhillite group" together with leadhillite and macphersonite with the system no. 5.BF.40 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns susannite to the class of "carbonates, nitrates and borates" and there in the section of "composite carbonates". Here he can be found as the only member of the unnamed group 01/17/03 within the sub-section “ Compound carbonates with different formulas ”.

Crystal structure

Susannite crystallizes in the space group P 3 (space group no. 143) with the lattice parameters a  = 9.07  Å and c  = 11.57 Å as well as 3 formula units per unit cell . Template: room group / 143

properties

Some susannites show a strong lemon-yellow fluorescence under UV light .

When heated on charcoal in front of the soldering tube , susannite swells a little, turns yellow and reduces to lead. In nitric acid , the mineral dissolves with a fizz, releasing carbon dioxide . The poorly soluble lead sulfate that remains forms a white precipitate .

Modifications and varieties

The compound Pb 4 [(OH) 2 | (CO 3 ) 2 | SO 4 ] is trimorphic and, in addition to the trigonal crystallizing susannite, occurs in nature as monoclinic crystallizing leadhillite and as orthorhombic crystallizing macphersonite .

Education and Locations

Susannite crystal from the Lautenthal smelting works (slag heap), Harz, Lower Saxony, Germany (image size: 4 × 4 mm)

Susannite forms as a secondary mineral in the oxidation zone of lead-containing deposits at a temperature of over 80 ° C. Accompanying minerals are other lead minerals such as B. caledonite , cerussite , lanarkite , leadhillite and macphersonite .

As a rare mineral formation, susannite could only be detected at a few sites so far (status: 2011). About 100 sites are known (as of 2015). In addition to its type locality "Susanna Mine", the mineral occurred in the United Kingdom in several mines at Caldbeck Fells and in the quarry at Whitwell in the English county of Cumbria ; in several mines at Leadhills and Wanlockhead in Scotland and in many mines in the Welsh region of Ceredigion .

In Germany, Susannite was found in the Black Forest , among other places ; on the slag dump near Richelsdorf and in the "Grube Vereinigung" near Eisenbach in Hesse; at several locations in the Harz region of Lower Saxony ; in various pits or on slag heaps in North Rhine-Westphalia ; in several places in Rhineland-Palatinate and in the "Holy Trinity" mine near Zschopau in the Saxon Ore Mountains.

The only previously known site in Austria is Arzberg am Semmering in Hasental near the Styrian community of Spital am Semmering .

Other locations include France, Greece, Ireland, Italy, Namibia, Romania, Russia, the Czech Republic and the United States of America (USA).


See also

literature

Web links

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

Individual evidence

  1. ^ A b W. Haidinger : Second class: Geogenide. II. Order. Barytes. VII. Lead base. Suzannit , in: CF Rammelsberg (Ed.): Handbook of Determining Mineralogy , Verlag von Wilhelm Engelmann, Leipzig 1860, pp. 499–506 ( PDF 512 kB )
  2. ↑ 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.  303 .
  3. ↑ a b c Susannite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 64.3 kB )
  4. ↑ a b Webmineral - Susannite
  5. ↑ 5. Sulphato-tricarbonate of lead , in: The London and Edinburgh Philosophical Magazine and Journal of Science , Vol.XVI , January-June 1840 in the Google book search
  6. ↑ Leadhillit (and Susannit) , in: CF Rammelsberg (ed.): Handbuch der Mineralchemie , Verlag von Wilhelm Engelmann, Leipzig 1860, p. 297
  7. ↑ Mindat - Number of localities for Susannite
  8. ↑ Find location list for susannite at the Mineralienatlas and at Mindat