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Sylvite

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François Sylvius de le Boe
Formula:
KCl
System:
Isometric
Colour:
Colourless, grey, white, ...
Lustre:
Vitreous
Hardness:
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

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
3.AA.20

3 : HALIDES
A : Simple halides, without H2O
A : M:X = 1:1, 2:3, 3:5, etc.
9.1.1.2

9 : NORMAL HALIDES
1 : AX
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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First Recorded Occurrence of Sylvite

Year of Discovery:
1832
Geological Setting of First Recorded Material:
Evaporite deposit

Occurrences of Sylvite

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

Physical Properties of Sylvite

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:
1.993(5) g/cm3 (Measured)    1.987 g/cm3 (Calculated)

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:
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:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Sylvite

Type:
Isotropic
RI values:
n = 1.4903
Max 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:
All elements listed in formula:
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

3.AA.05MarshiteCuI
3.AA.05Miersite(Ag,Cu)I
3.AA.05NantokiteCuCl
3.AA.05UM1999-11:I:CuSCu(I,S)
3.AA.10IodargyriteAgI
3.AA.10Tocornalite(Ag,Hg)I
3.AA.15BromargyriteAgBr
3.AA.15ChlorargyriteAgCl
3.AA.20CarobbiiteKF
3.AA.20GriceiteLiF
3.AA.20HaliteNaCl
3.AA.20VilliaumiteNaF
3.AA.25SalammoniacNH4Cl
3.AA.25UM1998-03-Cl:TlTlCl
3.AA.25LafossaiteTl(Cl,Br)
3.AA.30Calomel(Hg22+)Cl2
3.AA.30Kuzminite(Hg22+)(Br,Cl)2
3.AA.30Moschelite(Hg22+)I2
3.AA.35NeighboriteNaMgF3
3.AA.40ChlorocalciteKCaCl3
3.AA.45KolaritePbTeCl2
3.AA.50RadhakrishnaitePbTe3(Cl,S)2
3.AA.55ChallacolloiteKPb2Cl5
3.AA.60HephaistositeTlPb2Cl5

Other Names for Sylvite

Other Information

Thermal Behaviour:
Melts at 790°. Highly diathermanous.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
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

Localities for Sylvite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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