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|System:||Monoclinic||Colour:||Colorless, white; ...|
|Hardness:||3 - 3½|
|Name:||Named magnesium-chlorophoenicite in 1935 by Charles Palache in allusion to the dominance of Mg over Mn in the composition and its relationship to Chlorophoenicite. Name was changed by the IMA to magnesiochlorophoenicite.|
Magnesium analogue of Chlorophoenicite. To date only a few specimens are known with Mg>Mn. Formerly, magnesiochlorophoenicite was a name commonly given to specimens of this series and hundreds of specimens in old collections are so labeled, but recent quantitative chemical surveys have failed to find more than a few verified specimens, all but one of which are from Franklin. The remaining verified specimen is from Ogdensburg and it is still unique. In general, specimens formerly labeled magnesium chlorophoenicite or magnesiochlorophoenicite have been proven to be misidentified and the specimens are almost always Mn-dominant chlorophoenicite, the very abundant end-member. There is no identification value relating to the apparent thickness of crystals as has been attributed by folklore. Chemical analysis is the only definitive method of validation.
Classification of Magnesiochlorophoenicite
|Nickel-Strunz 10th (pending) edition ID:||8.BE.35|
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
E : With only medium-sized cations, (OH, etc.):RO4 > 2:1
|Dana 8th edition ID:||126.96.36.199|
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
1 : (AB)m(XO4)pZq, where m:p > 4:1
|Hey's CIM Ref.:||20.8.19|
20 : Arsenates (also arsenates with phosphate, but without other anions)
8 : Arsenates of Mn
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Type Occurrence of Magnesiochlorophoenicite
|Type Locality:||Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA|
|Year of Discovery:||1935|
|Geological Setting of type material:||In secondary veinlets in massive ore in a metamorphosed Pre-cambrian sedimentary Zn-Fe-Mn deposit.|
|Associated Minerals at type locality:|
Physical Properties of Magnesiochlorophoenicite
|Colour:||Colorless, white; colorless in transmitted light.|
|Hardness (Mohs):||3 - 3½|
Lengthwise to fibers, perfect.
|Density (measured):||3.37 g/cm3|
|Density (calculated):||3.18 g/cm3|
|Comment:||Density discrepancy probably due to acicular crystals, small size, and surface tension leading to error.|
Crystallography of Magnesiochlorophoenicite
|Class (H-M):||2/m - Prismatic|
|Cell Parameters:||a = 23.02Å, b = 3.3Å, c = 7.34Å|
β = 106.22°
|Ratio:||a:b:c = 6.976 : 1 : 2.224|
|Unit Cell Volume:||V 535.40 Å³ (Calculated from Unit Cell)|
|Morphology:||Occurs as acicular crystals randomly arranged or in radial aggregates of fibrous crystals.|
|X-Ray Powder Diffraction:|
|Comments:||38-1438, also Journal of Powder Diffraction 2:225 (1987).|
Optical Data of Magnesiochlorophoenicite
|RI values:||nα = 1.669 nβ = 1.672 nγ = 1.677|
|Maximum Birefringence:||δ = 0.008|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
|Dispersion:||generally r < v strong, also r > v|
Chemical Properties of Magnesiochlorophoenicite
|Simplified for copy/paste:||(Mg,Mn)3Zn2(AsO4)(OH,O)6|
|Essential elements:||As, H, Mg, O, Zn|
|All elements listed in formula:||As, H, Mg, Mn, O, Zn|
|Analytical Data:||High Mg analyses are unknown and qualitative analysis are insufficient to verify the species. Maximum measured Mg:Mn:Zn = 1.00 : 0.85 : 0.31 One of the designated type specimens was not Mg dominant and was therefore misidentified (CM 1981, p. 335).|
Relationship of Magnesiochlorophoenicite to other Species
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Magnesiochlorophoenicite
|Fluorescence in UV light:||Not fluorescent|
Display Requirements from:
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Magnesiochlorophoenicite
Palache, C. (1935) USGS Professional Paper 180: 124.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 780.
American Mineralogist (1968): 53: 1110-1119.
Dunn, P. J. (1981): Magnesium-chlorophoenicite redefined and new data on chlorophoenicite. Canadian Mineralogist: 19: 333-336.
Internet Links for Magnesiochlorophoenicite
Localities for Magnesiochlorophoenicite
The 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.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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