martes, marzo 20, 2007
In october, 2003, and using the chilean legal framework concerning to the Mining Code applying on the territory of Chile, a multidisciplinary group formed by five professionals, removed from "Comuna de San Joaquin" (San Joaquin Town) a more than Six Tons weird iron rock, from which people knew and heard about before 1918. Although Mayors and inhabitants near to the zone knew, for several decades, a lot about the Rock (with 6170 kilograms), and seem to them this Big Iron Rock was intriguing indeed, nobody spend time enough in its study, neither the Town Council nor the Chilean Government, nor the chilean institution known as "Consejo de Monumentos Nacionales" or even Sernageomin entity. Thus, because Mr. Jorge Veas Nuñez was the first man who discovered it, this Weird Iron Rock was termed as Veas-01.
Why Mr. Veas knew well this metal-stony iron had other origin than a man-made origin?. It must take into account than in the time from which people and Mayors heard for first time about such rock, there was no blast furnace with technologies enough to produce in Santiago city, or even in Chile at that time, low Carbon or low alloy steel, as further anayses revealed. The average carbon content in the iron of Veas-01 no exceeds 0.10 wt% and the purity of such iron is in between 98.55 and 99.15 wt%.
SECTIONS OF VEAS-01
The Big Iron Rock found in Chile consists in two different section with very diverse characteristics:
(1) an Outer Melt Crust: surrounding almost half the surface of Veas-01 samples indicate a quartz subsaturated mineralogy consistent of millimetric size olivines, pyroxenes, spinels (iron-magnesium chromites), leucite-moochiquite, possible melilite and minor undetermined calcium-aluminium (iron-rich exsolved with iron-poor potasium-rich) inclusions. There are many characteristics that fit well with Chondrite Groups (a class of meteorite), or even with Carbonaceous Chondrites, and the thin melt crust has a considerable portion of brecciated fragmented rocks in a metal and indingistic matrix. δ(17-O) vs δ(18-O) oxygen isotope analysis in subsamples from the melt crust do not plot exactly on terrestrial fractionation line (TFL) but below. The Oxygen Isotope Analysis of one sample of Veas-01 Iron Rock crust was made at the Department of Geology, Queen's University, in October 2005. The sample was personally taken from the Rock by Dr. Brian Townley. A brief report indicated that high δ(18-O) values indicate the samples have seen δ(18-O) enrichment, metamorphic, or have been altered at low temperatures. Crystalline texture (hexagonal) of the crust, the melt crust mineralogy and leucite-moochiquite intracrystalline filling, are suggestive of a high-temperature (more than 1600ºC) slow crystallizing process, not expected form industrial steel, much less for slag. In summary, oxygen isotope analysis, indicate values, both from whole rock and mineral, slightly below the terrestrial fractionation line (TFL), even within error margin. Proximity to the TFL has been reported for other meteorites, such as the Vesta (HED) Meteorites, in which data plot parallel to the TFL at differences below 0.5 for both, δ(17-O) and δ(18-O) respect to the TFL (Scott, 2001; Scott and Krot, 2001). High δ(18-O) may be explained by low temperature water-rich alteration on earth, yet high values like those measured for Veas-01 are also reported for Carbonaceous Chondrites of the CI type (Clayton, 1993). Oxygen isotope result do not outrule an extraterrestrial origin as initially thought, yet more samples of the Veas-01 crust, as well as fragments of the lower breccia should be taken for further analyses. Such melt crust forms about 3 wt% of the whole rock weight.
(2) an Inner Iron Matrix: it represents the 97 wt% fo the weight of Veas-01, consisting in pure iron, low Ni (0.20 wt%), and some well know inclusions found in meteorites such as Troilite (FeS), (Fe,Mn)S a family of Niningerite, and Chromite, among others. Those inclusions and some specific cracks indicate this metal suffered very high-pressures. Although Austenite in steels has FCC (Face Centered Cubic) structure, and it is no magnetic, in Veas-01 it has been found a strange, big and strong magnetic like-austenite grain, with a size of 2 or 5 mm. Since by definition austenite is not magnetic and with an order-size of 100 or 200 microns, some scientists believe this strange rion matrix was supposedly formed under high-pressures, maybe similar to those forming in the core of planets with a size similar to Earth's diameter. Nevertheless, micropores metal-material veins found at the iron matrix that change neutral pH 7 of water into the value pH 8.5, have suggested some kind of High-Temperature and High-Pressure Hydrothermal Synthesis.
Picture above: Weird Iron Rock discovered decades ago, and studied from october 2003. This Rock shows many characteristics which are compatible with known meteorites, except for lack on Ni in the portion of the rock. Here, the Geologist and Professor, Mr. Carlos Roeschmann Schneeberger, takes a look next to the Big Iron Rock found in Chile and known as Veas-01.
INSIGHT OF VEAS-01 AND OUTER MELT CRUST
At the beginning 2005, the geologist and scientist Dr. Brian Townley carried out a report and personal data review concerning micropetrographic, SEM and microprobe sudies of selected samples of the Veas-01 Iron Rock, together with results of other analysis reported independently in past years. Dr. Townley also include data results of oxygen isotope study carried out on melt crust samples, at the Department of Geology, Queen's University at Kingston, Ontario. This rock, has been center of research effort by Mr. Jorge Veas and his team, with collaboration on Brian Townley part. All research expenses have been incurred by Mr. Veas and group. Samples for micropetrographic and isotopic study personally was taken by Dr. Townley from the Veas-01 Iron Rock in company of Mr. Jorge Veas and Mr. Carlos A. Hidalgo.
As it has been mentiones before, Veas-01 consists mostly of iron, with a outer melt crust and many inclusions of silicate rocks. The rock itself weighs approximately 6.2 metric tons, measuring some 2.5 by 2.0 by 1.5 meters, and as it has been measured by physicist engineer Mr. Jorge Reyes Molina and by Dr. Brian Townley, the Rock is strongly magnetic.
Two thin polished sections of the outer melt crust were studied, and one additional crust sample was sent to Queen's University for oxygen isotope study. Thin polished sections were prepared and sutied at the Department of Geology, University of Chile.
The main objectives of Dr. Townley's report was to provide additional insight with respect to possible origin of the Veas-01 Iron Rock, by use of existing data as well as new analytical results of the Veas-01 of oxygen isotopes.
Two outer selt crust samples were taken from Veas-01; a sample labeled as Oliv01 and other labeled as Oliv02. Melt crust on the rock varies from one point to the other, well developed and about 5 - 8 mm thick in one side (from which samples were taken), and very thin and poorly developed on the other side. In some parts crust looks dark and glassy (sample Oliv02), in other parts it looks slightly granular (sample Oliv01), and in other parts granular, with macroscopic iron sulfides (perhaps pyrrotite or pyrite) or magnetite.
Sample Oliv01 consists of millimetric sized olivine, melilite and pyroxened in equigranular texture, with abundant smaller opaque minerals (iron oxides, chromites and sulfides) and leucite-moochiquite fillings. Minor alteration to chlorite is observed along crystal contacts and fillings, particularly piroxened. A portion of this sample, analyzed by X-ray diffraction at Universidad de Santiago (USACH), indicated fayalite (iron silicate gamma) and monticellite as the olivines, together with quartz and gohetite (Garin, 2005).
Sample Oliv02 consists of millimetric sized chromites and olivines (monticellite) in a ground mass of smaller crystallines olivines (monticellite-fayalite). Smaller opaque minerals comprise iron oxides and chromites.
Both sam`ples present effects of weathering, in particular oxidation of iron and of chromites, which make direct petrographic identification of mineral some what difficult. For better identification, microprobe analysis were carried out on the sample. In sample sent to Queen's University, melilite was reported in addition to monticellite, only suspected in sample Oliv02.
SEM AND MICROPROBE ANALYSIS
A total of two samples from the outher melt crust were analyzed, data presented in other reports. Micropetrographic studies of samples Oliv01 y Oliv02 indicate a silicate and oxide mineralogy (olivine, pyroxene, leucite and chromites).
Microprobe analysis form sample Oliv02 inicates the following mineralogy: fayalite, hedenbergite (or hastingsite or essenite), leucite and possibly ringwoodite. Some secondary alteration chlorite occurs between olivine crystals, as well as idingsite-boulingite. Sample Oliv02 shows the following mineralogy: iron-magnesium chromites (spinels), from magnesium-rich to iron-rich, intergrown with iron-magnesium olivines, with rounded inclusions of unknown minerals. These present a fishbone-like texture of light and dark colored minerals. Microprobe analysis show two differing minerals ans undetermined aluminosilicates, a light colored Fe-Ca-Ti-Mg aluminosilicate in a dark colored Ca-K-Fe-Na aluminosilicate. The light colored mineral is iron-rich, the dark not, but both have high calcium and aluminium, relative to other minerals of the melt crust.
In summary, melt crust samples have a quartz subsatured mineralogy consistent of millimetric size olivines, pyroxenes, spinels (iron-magnesium chromites), leucite-moochiquite, melilite, and minor undetermined calcium-aluminium (iron-rich exsolved with iron-poor potasium-rich) inclusions.
OXYGEN ISOTOPE ANALYSIS
One sample of Veas-01 crust was sent to Queen's University, in October 2005. The sample was taken personally by Dr. Townley form the rock. Two analysis were reported from Queen's one, one analysis on what is thought melilite, and one on a whole rock subsample. Results are the following:
Subsample : δ(17-O) ; δ(18-O)
Whole Rock (WR): 6.0 +-0.2 ; 12.0 +- 0.2
Melilite : 7.8 +-0.2 ; 15.7 +- 0.2
A brief report indicated that all terrestrial and moon samples have a δ(17-O)=0.52 x δ(18-O) and most extraterrestrial samples do not, having excess or depletion on 17-O. These samples plot right on the terrestrial fractionation line (error is +-0.2) and are very unlike to be of extraterrestrial origin. Moreover, high δ(18-O) values indicate thay have seen water enriched on δ(18-O) (metamorphic) or have been altered at low temperatures.
Nevertheless, closer examination of data and plotting, compared to the terrestrial fractionation line (as described above), show that even within error margin these samples do not fall on the line, they occur slightly below. The whole rock subsample falls closest to the line, whereas melilite subsample do further away, yet, error bars for both do not intercept the fractionation line.