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Sylvite

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Formula:
KCl
System:IsometricColour:Colourless, grey, white, ...
Lustre:VitreousHardness:1½ - 2
Name:
From Latin "sal digestibus Sylvii", salts of Sylvius, named after François Sylvius de le Boe (1614-1672), a physician and chemist of Leyden, Netherlands.

Classification of Sylvite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:3/A.02-40
Nickel-Strunz 10th (pending) edition ID:3.AA.20

3 : HALIDES
A : Simple halides, without H2O
A : M:X = 1:1, 2:3, 3:5, etc.
Dana 8th edition ID:9.1.1.2

9 : NORMAL HALIDES
1 : AX
Hey's CIM Ref.:8.1.6

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
1 : Halides of the alkali metals and ammonium
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Type Occurrence of Sylvite

Type Locality:Mt Vesuvius, Somma-Vesuvius Complex, Naples Province, Campania, Italy
Year of Discovery:1832
Geological Setting of type material:Evaporite deposit

Occurrences of Sylvite

Geological Setting:Evaporites in sedimentary basins, sublimate in volcanic fumaroles, burning coal.

Physical Properties of Sylvite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent, Translucent
Colour:Colourless, grey, white, yellowish to reddish, seldom blue or violet
Streak:White
Hardness (Mohs):1½ - 2
Tenacity:Brittle
Cleavage:Perfect
On {001}
Fracture:Irregular/Uneven
Density (measured):1.993(5) g/cm3
Density (calculated):1.987 g/cm3

Crystallography of Sylvite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fm3m
Cell Parameters:a = 6.2931Å
Unit Cell Volume:V 249.23 ų (Calculated from Unit Cell)
Z:4
Morphology:Crystals cubic; cubo-octahedral or octahedral habits less common. Massive, coarsely granular to compact. Columnar structure rare; as crusts.
Twinning:On {111} (artificial crystals only).

Epitaxial Relationships of Sylvite

Epitaxial Minerals:
Hematite
Fe
 
2
O
 
3
Halite
NaCl
Epitaxi Comments:Hematite inclusions with {0001} of hematite parallel to {001}, {111}, or {011} of halite. Minute halite inclusions oriented in parallel position to the sylvite.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Sylvite

Type:Isotropic
RI values: n = 1.4903
Maximum Birefringence:δ = 0.000 - Isotropic minerals have no birefringence
Surface Relief:Moderate
Type:Isotropic
Pleochroism:Visible
Comments:Distinct pleochroism observed in colored crystals with weak anomalous birefringence (especially noted in mechanically deformed crystals).
Comments:Anomalously anisotropic when strained

Chemical Properties of Sylvite

Formula:
KCl
Essential elements:Cl, K
All elements listed in formula:Cl, K
CAS Registry number:7447-40-7

CAS Registry numbers are published by the American Chemical Society
Analytical Data:Water soluble. Taste salty but more astringent than halite.
Common Impurities:Br,CO2=C,O

Relationship of Sylvite to other Species

Common Associates:
PolyhaliteKieseriteKainiteHaliteGypsum
CarnalliteAnhydrite
Related Minerals - Nickel-Strunz Grouping):

- +
3.AA.05Marshite
CuI
3.AA.05Miersite
(Ag,Cu)I
3.AA.05Nantokite
CuCl
3.AA.05UM1999-11:I:CuS
Cu(I,S)
3.AA.10Iodargyrite
AgI
3.AA.10Tocornalite
(Ag,Hg)I
3.AA.15Bromargyrite
AgBr
3.AA.15Chlorargyrite
AgCl
3.AA.20Carobbiite
KF
3.AA.20Griceite
LiF
3.AA.20Halite
NaCl
3.AA.20Villiaumite
NaF
3.AA.25Salammoniac
NH
 
4
Cl
3.AA.25UM1998-03-Cl:Tl
TlCl
3.AA.25Lafossaite
Tl(Cl,Br)
3.AA.30Calomel
(Hg
+
2
)Cl
 
2
3.AA.30Kuzminite
(Hg
+
2
)(Br,Cl)
 
2
3.AA.30Moschelite
(Hg
+
2
)I
 
2
3.AA.35Neighborite
NaMgF
 
3
3.AA.40Chlorocalcite
KCaCl
 
3
3.AA.45Kolarite
PbTeCl
 
2
3.AA.50Radhakrishnaite
PbTe
 
3
(Cl,S)
 
2
3.AA.55Challacolloite
KPb
 
2
Cl
 
5
3.AA.60Hephaistosite
TlPb
 
2
Cl
 
5
Related Minerals - Hey's Index Grouping:

- +
8.1.1Griceite
LiF
8.1.2Villiaumite
NaF
8.1.3Halite
NaCl
8.1.4Hydrohalite
NaCl · 2H
 
2
O
8.1.5Carobbiite
KF
8.1.7Salammoniac
NH
 
4
Cl

Other Names for Sylvite

Synonyms:
Chloride of PotassiumHoeveliteHöveliteLeopolditeMuriate of Potash
Potassium ChlorideSal digestivus sylviiSchätzeliteSilviteSylvin
SylvineSylvyne
Other Languages:
German:Chlorkalium
Hoevelit
Hövellit
Leopoldit
Schätzelit
Sylviit
Sylvit
Russian:Сильвин
Simplified Chinese:钾盐
钾石盐
Spanish:Hoevelita
Hövelita
Leopoldita
Schätzelita
Sylvita

Other Information

Thermal Behaviour:Melts at 790°. Highly diathermanous.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
External LinksSearch for toxicity information at the United States National Library of Medicine
Industrial Uses:Source for potasium

References for Sylvite

Reference List:

- +
Bischoff (1865), Berg.- und hüttenmännisches Zeitung, Freiberg, Leipzig: 24: 276.

Bischoff (1865), Ann. Chem. Phys.: 5: 318.

Zinken (1865), Berg.- und hüttenmännisches Zeitung, Freiberg, Leipzig: 24: 79.

Rubens and Snow (1892), Annalen der Physik, Halle, Leipzig: 46: 529.

Rubens et al (1897), Annalen der Physik, Halle, Leipzig: 60: 418.

Martens (1902), Annalen der Physik, Halle, Leipzig: 8: 459.

Johnston-Lavis (1906), Nature: 74: 174.

Bragg (1913), Proceedings of the Royal Society of London: 89: 448.

Strukturber (1931): 1: 105.

Panichi U. (1933), Sul dimorfismo del salgemma e della silvite. Periodico di Mineralogia (Roma), pp.25-33.

Palache, Charles, Harry Berman & Clifford Frondel (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Seventh edition, Volume II: 7-9.

Bedarida F., Della Giusta A.(1970), Dislocazioni a vite in cristalli aciculari di KCl; effeti sulle misure delle intensita dei raggi X. Periodico di mineralogia (Roma), pp.137-143.

Internet Links for Sylvite

Search Engines:
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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Sylvite details from Handbook of Mineralogy (PDF)
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  • Localities for Sylvite

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