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365:, with a space group of Fd3m. The point symmetry can be three possibilities; 4*3m, 3*m, or mm. Within the oxygen sub-lattice of ceylonite, the Mg ions occupy tetrahedral 4c symmetry positions, and the Al ions occupy octahedral 8f site. This allows for the remaining octahedral site to be open for defects, causing a variety in structure and physical properties.
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The ceylonite first discovered on the island of Ceylon, modern day Sri Lanka, was found imbedded in calcareous spar, and accompanied by pyrite and micas. The crystals were located in a low lying dried up river, and were relatively shallow in the soil; 8 to 10 inches. On one side of the bank a mass of
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Ceylonite can actually undergo a solid solution series in which the composition changes, but it is still ceylonite. Magnesium rich ceylonite can undergo an increase in iron that will replace the magnesium cation in the A-block, therefore making the new composition
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The grains in the first discovered ceylonite looked of compacted soils, leading one to believe they were perhaps sedimentary in formation. This was an early hypothesis, and did not hold true after further analysis.
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Ball, J.A., Murphy, S.T., Grimes, R.W., Bacorisen, D., Smith, R., Uberuaga, B.P., Sickafus, K.E., June 2008, Defect processes in MgAl2O4 spinel, Solid State
Sciences, 10, 6, 717-724.
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for 'abundant,' for its many crystal forms, and is distinguished chemically by low Mg:Fe ratios of approximately 1:3. It is sometimes used as a gemstone.
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Desa, M., Ramana, M.V., Ramprasad, T., 30 June 2006, Seafloor spreading magnetic anomalies south off Sri Lanka, Marine
Geology, 229, 34, 227-240.
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Ceylonite and pleonaste are historical terms in mineralogy. Nevertheless, both terms are used in the current mineralogical literature.
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Sickafus, K. E., Wills, J. M. and Grimes, N. W. (1999), Structure of Spinel. Journal of the
American Ceramic Society.
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Gribble, C.D. (1988). The non-silicate minerals. In: Rutley’s
Elements of Mineralogy. Springer, Dordrecht. P. 281.
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Skeen, George J.A. (1887) Journal of the Ceylon Branch of the Royal
Asiatic Society, Volume IL-Part L No. 4, 97-98
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Precious stones and gems, their history and distinguishing characteristics By Edwin
William Streeter, p.33-34
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The Mg-ceylonite has a much more reliable study of its geological occurrence. It is found in Mg and Al rich
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King, R. J. (2004). Minerals explained 40: The spinels. Geology Today, 20(5), 194-200.
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361:, where cation is Mg or Fe. This formula creates a face centered cubic
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The mineral ceylonite has the chemical composition of (Mg, Fe) Al
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Spinels, 1992, Physics and
Chemistry of the Earth, 18, 105-125.
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Nonmagnetic, non-radioactive, sometimes fluorescent (red)
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Various; red to blue to mauve, dark green, brown, black
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301:are dingy blue or grey to black varieties of
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441:https://doi.org/10.1007/978-94-011-6832-8_8
66:Learn how and when to remove this message
29:This article includes a list of general
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353:Ceylonite has the structural formula Al
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305:. Ceylonite, named for the island of
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313:iron. Pleonaste is named from the
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390:was exposed, on the other, a
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228:Transparent to translucent
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293:(first cited 1793) and
111:Spinel structural group
50:more precise citations.
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281:Other characteristics
243:Optical properties
185:Conchoidal, uneven
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165:Cubic, octahedral
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503:Spinel gemstones
488:Mindat pleonaste
483:Mindat ceylonite
478:Gemdat ceylonite
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413:metamorphic rock
252:Refractive index
234:Specific gravity
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335:spinel group
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108:Spinel group
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321:Composition
262:Pleochroism
256:1.770-1.780
224:Diaphaneity
48:introducing
427:References
381:Occurrence
272:Solubility
191:Mohs scale
175:Indistinct
31:references
349:Structure
295:pleonaste
291:Ceylonite
246:Isotropic
142:Isometric
125:(Mg,Fe)Al
81:Ceylonite
497:Category
299:pleonast
208:Vitreous
194:hardness
181:Fracture
171:Cleavage
100:Category
419:History
395:granite
392:graphic
238:3.6–3.9
198:7.5–8.0
117:Formula
95:General
44:improve
388:gneiss
311:ferric
307:Ceylon
303:spinel
266:Absent
214:Streak
204:Luster
33:, but
315:Greek
218:White
152:Color
398:vein
369:FeAl
276:none
499::
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375:4
373:O
371:2
359:4
357:O
355:2
343:4
341:O
339:2
331:4
329:O
327:2
131:4
129:O
127:2
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