Among the natural hazards that "descend from the sky" are meteorites. Their stone-mineral nature from cosmic space is a real challenge to their research by different science specialists, but among them, very especially for geologists, because it allows them to reveal and discover similarities and differences with the main matter (rocks and minerals ) object of study of Geology, here on Earth; and with the objective, in addition, of its possible future use; because what can be defined today as "of pure scientific interest only", tomorrow may become "of a useful practical application". Every danger, then, has its benefit, profit and utility.
The constant increase in geological knowledge can be enriched by the study of this matter cosmic mineral premium and hence, also, is the interest aroused by the recent phenomenon of the fall of a meteorite in the Viñales region, one of the most popular tourist poles in the country. Hence the importance of making known to the broad public, the most elementary data on these species.
What is a meteorite?
A meteorite is nothing more than a part of a celestial body that comes from some part of the cosmic space, falls on the surface of a planet and does not completely disintegrate in its atmosphere. Now, on planet Earth, inhabited by conscious men, it is called the luminosity it leaves when it disintegrates when it reaches or penetrates the atmosphere before falling to the surface of the planet and is called meteor. The term meteor comes from the Greek μετέωρος meteors, which means "phenomenon in the sky." Therefore, the term is used both to describe the light flash that accompanies the fall of matter from the solar system on the Earth's atmosphere, and to that matter itself.
Memories of childhood influenced by dolls, made them call these phenomena, aeroliths, which even today some consider as a synonym for meteorite. An aeroliths is literally an "aerial stone," being a celestial body of rocky or rocky nature that penetrates the atmosphere and can be recovered on the earth's surface. However, they are now technically defined as pieces of disintegrated comets. This definition allows us to move to the classification of meteorites.
Since time immemorial, meteorites were known, but not in the concept as they are known today. In ancient Greece and Rome, Aristotle, Seneca and Pliny the Elder sensed that they were celestial bodies, but thought they were of earthly origin or even that the Gods threw stones at each other.
In the Middle Ages the Christian world had them as divine signs: when a meteorite fell it was delivered to the ipso facto church, without questioning anything else. This stage lasted until 1794, when the German physicist Ernst Florens Friedrich Chladni made the first scientific report on meteorites, which although rejected because "the stones cannot fall from Heaven, because in Heaven there are no stones," according to his opponents of the time, the evidence showed subsequent meteorite falls from precisely the sky, and such existence had to be accepted, and this led, of course, to the scientific classification of the different types of meteorites.
From Ernst Chladni the meteorites were classified as three types, according to their most evident characteristics in:
- Stony (also called rocky),
- metallic (also called iron, iron, and ferrous, iron, iron), and Metallic - rocky (also called: siderolith, mixed, iron of rocky type, iron-ferrous, petro-ferrous, rocky-metallic, lithosiderites, stonymetallic, "stony-irons").
In later years, using the rudimentary chemical analyzes of then, sub-types was created. This classification lasted until about 1970, when new techniques appeared, namely, powerful electron microscopes and chemical isotope analyzes. Then, they realized that the classical classification was not enough to determine the huge variety of meteorites they encountered.
The refinement of electron microscopes in the 70s and the new techniques of isotope analysis by laser spectrometry have allowed to carry out deeper and deeper chemical analyzes at the level of isotopes, with which meteorites that were under the same classification, it was discovered that they had completely different origins and eras of formation. Thanks to these discoveries, two other classifications were created that complemented aspects not included in the classifications in vogue: in one the meteorites are classified by the force of the shock they have suffered and in the other it refers to the meteorite's exposure to the climate. An example of application is in metal meteorites, which over time oxidize and deteriorate upon contact with air. With this classification you can define the degree of weathering of a specimen.
In summary, three different classifications are currently used to classify a meteorite:
- shock metamorphism,
- weathering, and
- by composition and origin.
The three complement each other.
Meteorites in Cuba. In Cuba, up to the present, with the last fall of the Viñales meteorite, 7 meteor falls are recognized.
1) In the area of Mango Jobo, province of Pinar del Río in 1938, 3 fragments of meteorites were found.
2) In Bacuranao, province of Havana; August 1974.
Meteorito de Bacuranao
3) In Palmarito, province of Cienfuegos, fell 1994, in the courtyard of a peasant family.
4) He appeared on the road to El Globo, in Calabazar, Boyeros; February 1996.
5) The one found in El Balcón de La Lisa, in 2001.
6) The one found in a plowed field in Güira de Melena, about 20 centimeters deep, also in 2001.
7) The recent meteorite of Viñales, evidently fragmented for having exploded in the air before falling to the surface and that its petrographic mineralogical study is being carried out at the Institute of Geology and Paleontology (PGI).
Fragment of the Viñales meteorite.
Finally, it is timely and correct to point out and make known the contribution made by our partner, the chemical engineer and Aggregate Researcher of the IGP. José Antonio Alonso Pérez, in the certification of the meteorites of the Globe, the Balcony of La Lisa and that of Güira de Melena. Bibliography used:
- Meteorites, in https / es.wikipedia.org / wiki
- Meteorito, in www.ecured.cu
- Classification of Meteorites, in https / es.wikipedia.org / wiki
- Iturralde Vinent, Manuel. Preliminary report on the Mineralogy of the Viñales meteorite, at www.cubadebate.cu
- Peláez, Orfílio. Have meteorites fallen in Cuba?, on www. Granma.cu/science/2018 Havana, February 5, 2019