elementos químicos

Alótropos

La lonsdaleíta es un alótropo hexagonal de carbono encontrado en meteoritos, así llamado en honor de Kathleen Lonsdale. Es una forma semejante al diamante, sin embargo hexagonal (polimorfo).

Encontrada por primera vez en 1967 en cristales microscópicos asociados al diamante en restos de meteorito en Arizona. Se cree que en el impacto del meteorito con grafito contra la tierra, el calor y la energía del impacto puedan transformar el grafito en diamante manteniendo su estructura hexagonal.

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Encontrada en Tunguska, Rusia y en otros impactos de meteoritos.

Aparece en resultados de estudios ejecutados en febrero del 2009, que la lonsdaleita sería un 58 % más dura que el diamante. Sería, por tanto, uno de los materiales más duros presentes en la naturaleza, junto al Nitruro Bórico de Wurtzita (wBN), producto de las presiones en erupciones volcánicas.

Lonsdaleíta
Lonsdaleíta
General
Categoría	Minerales elementos
Clase	1.CB.10b (Strunz)
Fórmula química	C
Propiedades físicas
Lustre	Adamantino
Transparencia	Transparente
Sistema cristalino	Hexagonal
Dureza	>10 (Mohs)

Lonsdaleite

Popigai impact crater, Popigai river, Anabarskii massif, Krasnoyarsk Territory, Eastern-Siberian Region, Russia

Kathleen Lonsdale

Formula:

C

System:

Hexagonal

Colour:

Transparent ...

Hardness:

7 - 8

Name:

For Dame Kathleen Lonsdale (1903-1971), Irish crystallographer who established the structure of benzene by X-ray diffraction methods in 1929. She also worked on the synthesis of diamonds, and was a pioneer in the use of X-rays to study crystals.

Polymorph of:

Chaoite, Diamond, Graphite

A questionable allotrope of carbon based on a hexagonal lattice.
Németh et al. (2014) consider lonsdaleite to be a faulted and twinned cubic diamond.

Classification of Lonsdaleite

IMA status:

Approved

Strunz 8th ed.:

1/B.02-50

Nickel-Strunz 10th (pending) ed.:

1.CB.10b

1 : ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)
C : Metalloids and Nonmetals
B : Carbon-silicon family

Dana 7th ed.:

1.3.5.3

Dana 8th ed.:

1.3.6.3

1 : NATIVE ELEMENTS AND ALLOYS
3 : Semi-metals and non-metals

Hey's CIM Ref.:

1.27

1 : Elements and Alloys (including the arsenides, antimonides and bismuthides of Cu, Ag and Au)

mindat.org URL:

http://www.mindat.org/min-2431.html
Please feel free to link to this page.

Type Occurrence of Lonsdaleite

Type Locality:

Canyon Diablo meteorite, Meteor Crater and vicinity, Winslow, Coconino Co., Arizona, USA

Year of Discovery:

1967

Geological Setting of Type Material:

Meteorite

Occurrences of Lonsdaleite

Geological Setting:

In meteorites and kimberlite.

Physical Properties of Lonsdaleite

Lustre:

Adamantine

Diaphaneity (Transparency):

Transparent

Colour:

Transparent brownish-yellow, grayish

Hardness (Mohs):

7 - 8

Hardness Data:

Measured

Comment:

imperfections in natural Lonsdaleite reduce hardness, artificial material has tested harder than diamond (>10) , See Physical Review letters (2009)

Density:

3.2 g/cm³ (Measured)    3.51 g/cm³ (Calculated)

Crystallography of Lonsdaleite

Crystal System:

Hexagonal

Class (H-M):

6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal

Space Group:

P6₃/mmc

Cell Parameters:

a = 2.51Å, c = 4.12Å

Ratio:

a:c = 1 : 1.641

Unit Cell Volume:

V 22.48 ų (Calculated from Unit Cell)

Z:

4

Morphology:

Fine grained aggregates

Optical Data of Lonsdaleite

Type:

Uniaxial (+/-)

RI values:

n_α = 2.404 n_β = 2.404

Max Birefringence:

δ = 2.404

Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.

Surface Relief:

Very High

Chemical Properties of Lonsdaleite

Formula:

C

Essential elements:

C

All elements listed in formula:

C

Relationship of Lonsdaleite to other Species

Related Minerals - Nickel-Strunz Grouping):

1.CB.05b	Chaoite	C
1.CB.05a	Graphite	C
1.CB.05c	Fullerite	C60
1.CB.10a	Diamond	C
1.CB.15	Silicon	Si

Related Minerals - Hey's Index Grouping:

1.1	Copper	Cu
1.2	Silver	Ag
1.5	Gold	Au
1.6	Auricupride	Cu3Au
1.7	Tetra-auricupride	AuCu
1.8	Zinc	Zn
1.9	Cadmium	Cd
1.10	Danbaite	CuZn2
1.11	Zhanghengite	CuZn
1.12	Mercury	Hg
1.13	Kolymite	Cu7Hg6
1.14	Moschellandsbergite	Ag2Hg3
1.15	Eugenite	Ag11Hg2
1.16	Schachnerite	Ag1.1Hg0.9
1.17	Paraschachnerite	Ag3Hg2
1.18	Luanheite	Ag3Hg
1.19	Weishanite	(Au,Ag)3Hg2
1.20	Indium	In
1.21	Aluminium	Al
1.22	Khatyrkite	(Cu,Zn)Al2
1.23	Cupalite	(Cu,Zn)Al
1.24	Diamond	C
1.25	Graphite	C
1.26	Chaoite	C
1.28	Silicon	Si
1.29	Tin	Sn
1.30	Lead	Pb
1.31	Anyuiite	Au(Pb,Sb)2
1.31	Novodneprite	AuPb3
1.32	Leadamalgam	Pb0.7Hg0.3
1.33	Arsenic	As
1.34	Arsenolamprite	As
1.35	Paxite	CuAs2
1.36	Koutekite	Cu5As2
1.37	Domeykite	Cu3As
1.38	Algodonite	(Cu1-xAsx)
1.39	Novákite	Cu20AgAs10
1.40	Kutinaite	Ag6Cu14As7
1.41	Antimony	Sb
1.42	Stibarsen	AsSb
1.43	Paradocrasite	Sb3As
1.44	Horsfordite	Cu, Sb
1.45	Cuprostibite	Cu2(Sb,Tl)
1.46	Allargentum	(Ag1-xSbx)
1.47	Aurostibite	AuSb2
1.48	Dyscrasite	Ag3Sb
1.49	Bismuth	Bi
1.50	Maldonite	Au2Bi
1.51	Sulphur	S8
1.52	Rosickýite	S
1.53	Selenium	Se
1.54	Tellurium	Te
1.55	Chromium	Cr
1.56	Rhenium	Re
1.57	Iron	Fe
1.58	Chromferide	Fe3Cr1-x (x=0.6)
1.59	Ferchromide	Cr3Fe1-x
1.60	Wairauite	CoFe
1.61	Nickel	Ni
1.62	Kamacite	(Fe,Ni)
1.63	Taenite	(Fe,Ni)
1.64	Tetrataenite	FeNi
1.65	Awaruite	Ni3Fe
1.66	Palladium	(Pd,Pt)
1.67	Potarite	PdHg
1.68	Paolovite	Pd2Sn
1.69	Stannopalladinite	(Pd,Cu)3Sn2
1.70	Cabriite	Pd2CuSn
1.71	Taimyrite-I	(Pd,Cu,Pt)3Sn
1.72	Atokite	(Pd,Pt)3Sn
1.73	Rustenburgite	(Pt,Pd)3Sn
1.74	Zvyagintsevite	(Pd,Pt,Au)3(Pb,Sn)
1.75	Plumbopalladinite	Pd3Pb2
1.76	Osmium	(Os,Ir,Ru)
1.77	Iridium	(Ir,Os,Ru)
1.82	Platinum	Pt
1.83	Hongshiite	PtCu
1.84	Niggliite	PtSn
1.85	Isoferroplatinum	Pt3Fe
1.86	Tetraferroplatinum	PtFe
1.87	Tulameenite	Pt2CuFe
1.88	Ferronickelplatinum	Pt2FeNi
1.89	Rhodium	(Rh,Pt)

Related Minerals - Dana Grouping):

1.3.5.1	Diamond	C
1.3.5.2	Graphite	C
1.3.5.4	Chaoite	C
1.3.5.5	Fullerite	C60