Texas Astronomical Society Public Observing Coordinator Joe Vines
examines the suevite and shattercone exhibit at the Meteorite Petting Zoo.
Brownfield_6228_cropped
Thin section of a meteorite, prepared by Steve Schoner.
This image is almost a 1:1 macro made using crossed linear polarizers on the stage of an Illumitrans slide copier equipped with a Pentax istDS DSLR.
Image cropped slightly (horizontally).
Meteorite (Rumurutite, R3), NWA 4360
A cut fragment (about 4.87 gms) of the NWA 4360 meteorite, a Rumurutite, found near Morocco, Algeria. The total known weight of this meteorite is 308 gms and the total weight of all known Rumurutites is only about 3 kgms, making them rare among meteorites.
The Rumurutite clan is one of several groups of the ordinary chondrites. The round features visible in the polished surface are called chondrules. The darker, fine-grained material between the chondrules is a mineral matrix, composed of many smaller chondrules and clasts (fragmented inclusions) of other minerals.
Fine cracks, called veins, in these meteorites allow water and air to enter the matrix and oxidize the minerals. These are visible in the micrographs of a thin section (other frames in this set) cut from this fragment.
The largest chondrules visible in this frame are about 1mm in diameter, about one-third the field of view of the thin-section micrographs.
Thin section and fragment obtained from Hanno Strufe, of Pirmasens, Germany (www.strufe.net).
NWA-split-closeup-1509
These NWA (Northwest Africa) meteorites are unclassifed, but appear to belong to the chondrites, the most common form of meteorite.
They are unclassified as to location of fall, as well, other than that they were brought to market between 2000 and 2002 by Arab nomads from the deserts of Morocco.
In polished cross-section, you can see very fine chondrules (round inclusions), from which they get their type name. You also see very fine metallic flakes which appear to me to be mostly iron, with some copper.
Most have heavily weathered crusts (from desert exposure) and some fusion crust remaining on the lower sides, which were protected from erosion by wind-blown sand.
This is a macro closeup, shot at 1:1, showing the polished slice face (right) and surface (left) of the two halves of the same specimen shown in image 1595.
The flakes in the face at right are mostly iron crystals. The surface at left is not heavily weathered but does show significant oxidation of the iron content.
NWA-pair-lowkey-1617
These NWA (Northwest Africa) meteorites are unclassifed, but appear to belong to the chondrites, the most common form of meteorite. They are unclassified as to location of fall, as well, other than that they were brought to market between 2000 and 2002 by Arab nomads from the deserts of Morocco.
In polished cross-section, you can see very fine chondrules (round inclusions), from which they get their type name. You also see very fine metallic flakes which appear to me to be mostly iron, with some copper.
Most have heavily weathered crusts (from desert exposure) and some fusion crust remaining on the lower sides, which were protected from erosion by wind-blown sand.
These specimens measure:
Left -- 60 x 45 x 25 mm, weight: 70 grams
Right -- 56 x 30 x 30, weight 61 grams.
Both are heavily weathered and show iron and copper flakes in their polished surfaces.
NWA-both-halves-1595
These NWA (Northwest Africa) meteorites are unclassifed, but appear to belong to the chondrites, the most common form of meteorite. They are unclassified as to location of fall, as well, other than that they were brought to market between 2000 and 2002 by Arab nomads from the deserts of Morocco.
In polished cross-section, you can see very fine chondrules (round inclusions), from which they get their type name. You also see very fine metallic flakes which appear to me to be mostly iron, with some copper.
Most have heavily weathered crusts (from desert exposure) and some fusion crust remaining on the lower sides, which were protected from erosion by wind-blown sand.
These specimens measure:
Left -- 111 x 56 x 40, weight: 320 grams
Right -- 95 x 75 x 60, weight: 663 grams
and are from the same whole individual. It appears about 8 mm has been lost to the slice.
The specimens have a nice full fusion crust and are not much weathered, though there are some surface cracks.
See also image 1509 for a closeup of surface and polished face:
www.flickr.com/photos/chipdatajeffb/349315683/in/set-7215...
Ries-suevite-light-1608
This beautiful suevite is impact melt from the Ries Crater. It is a section about 20mm thick, by 150 x 120mm and weighs 509 grams. It is very fragile and already has crumbled by at least 40% of its original mass.
While it is primarily limestone, I can see various bits of chert and other minerals. It is quite colorful.
Ries-shattercone-1613
This fine large shattercone weighs 1,261 grams and measures 150 x 160 x 80 mm.
It is earthly limestone and shows fine horsetail patterns characteristic of shattercones. These patterns are formed when a tremendous impact sends shock waves through bedrock, instantly vaporising water embedded in crystalline silicates and driving the superheated steam through the rock.
About 15 million years ago a small asteroid impacted what is now a large plain in Germany, instantly vaporizing and excavating about 150 cubic kilometers of rock, leaving a crater which is today about 25 kilometers in diameter and several hundred meters deep. Little remains of the kilometer-sized asteroid but the area is rich in impact breccia (crushed Earth rock) and suevite (fused minerals and breccia).
Though known for hundreds of years as a circular "sea", the Ries Crater was not identified positively as an impact crater until the early 1960s, when American geologist Eugene Shoemaker and a colleage discovered that the local cathedral is made almost entirely of suevite quarried from the crater.
The crater walls are also rich in shattercones, another clear sign of an impact.
How big an impact? It's estimated that the blast had the force of 250,000 Hiroshima-class atomic bombs ...
This specimen from near the surface shows banded layers of breccia with shatter-cone striations.
It measures 90 x 70 x 40 mm and weighs 249 grams.
The largest known piece of this meteorite weighed more than 32 tons! It is estimated to have fallen betwen 2,800 and 6,000 years ago in the Gran Chaco Gualambra desert about 500 miles west-northwest of Buenos Aires, Argentina.
It was first reported by Spanish missionaries in 1576. Estimates of the date of fall are made from charred tree remains found in a small crater at a depth of about 10 meters.
Like the Canyon Diablo meteorite in Arizona and the Odessa meteorite, it is classifed as a coarse octahedrite (siderite), nickel-iron meteorite.
It measures 95 x 62 x 5 mm and weighs 172 grams.
This specimen is polished and coated to prevent corrosion and shows nice longitudinal crytals.
Campo-del-Cielo-slice1-1605
The largest known piece of this meteorite weighed more than 32 tons! It is estimated to have fallen betwen 2,800 and 6,000 years ago in the Gran Chaco Gualambra desert about 500 miles west-northwest of Buenos Aires, Argentina.
These NWA (Northwest Africa) meteorites are unclassifed, but appear to belong to the chondrites, the most common form of meteorite. They are unclassified as to location of fall, as well, other than that they were brought to market between 2000 and 2002 by Arab nomads from the deserts of Morocco.
In polished cross-section, you can see very fine chondrules (round inclusions), from which they get their type name. You also see very fine metallic flakes which appear to me to be mostly iron, with some copper.
Most have heavily weathered crusts (from desert exposure) and some fusion crust remaining on the lower sides, which were protected from erosion by wind-blown sand.
These specimens measure:
Left -- 60 x 45 x 25 mm, weight: 70 grams
Right -- 56 x 30 x 30, weight 61 grams.
Both are heavily weathered and show iron and copper flakes in their polished surfaces.
NWA-both-halves-1595
These NWA (Northwest Africa) meteorites are unclassifed, but appear to belong to the chondrites, the most common form of meteorite. They are unclassified as to location of fall, as well, other than that they were brought to market between 2000 and 2002 by Arab nomads from the deserts of Morocco.
In polished cross-section, you can see very fine chondrules (round inclusions), from which they get their type name. You also see very fine metallic flakes which appear to me to be mostly iron, with some copper.
Most have heavily weathered crusts (from desert exposure) and some fusion crust remaining on the lower sides, which were protected from erosion by wind-blown sand.
These specimens measure:
Left -- 111 x 56 x 40, weight: 320 grams
Right -- 95 x 75 x 60, weight: 663 grams
and are from the same whole individual. It appears about 8 mm has been lost to the slice.
The specimens have a nice full fusion crust and are not much weathered, though there are some surface cracks.
See also image 1509 for a closeup of surface and polished face:
www.flickr.com/photos/chipdatajeffb/349315683/in/set-7215...
Ries-suevite-light-1608
This beautiful suevite is impact melt from the Ries Crater. It is a section about 20mm thick, by 150 x 120mm and weighs 509 grams. It is very fragile and already has crumbled by at least 40% of its original mass.
While it is primarily limestone, I can see various bits of chert and other minerals. It is quite colorful.
Ries-shattercone-1613
This fine large shattercone weighs 1,261 grams and measures 150 x 160 x 80 mm.
It is earthly limestone and shows fine horsetail patterns characteristic of shattercones. These patterns are formed when a tremendous impact sends shock waves through bedrock, instantly vaporising water embedded in crystalline silicates and driving the superheated steam through the rock.
About 15 million years ago a small asteroid impacted what is now a large plain in Germany, instantly vaporizing and excavating about 150 cubic kilometers of rock, leaving a crater which is today about 25 kilometers in diameter and several hundred meters deep. Little remains of the kilometer-sized asteroid but the area is rich in impact breccia (crushed Earth rock) and suevite (fused minerals and breccia).
Though known for hundreds of years as a circular "sea", the Ries Crater was not identified positively as an impact crater until the early 1960s, when American geologist Eugene Shoemaker and a colleage discovered that the local cathedral is made almost entirely of suevite quarried from the crater.
The crater walls are also rich in shattercones, another clear sign of an impact.
How big an impact? It's estimated that the blast had the force of 250,000 Hiroshima-class atomic bombs ...
This specimen from near the surface shows banded layers of breccia with shatter-cone striations.
It measures 90 x 70 x 40 mm and weighs 249 grams.
The largest known piece of this meteorite weighed more than 32 tons! It is estimated to have fallen betwen 2,800 and 6,000 years ago in the Gran Chaco Gualambra desert about 500 miles west-northwest of Buenos Aires, Argentina.
It was first reported by Spanish missionaries in 1576. Estimates of the date of fall are made from charred tree remains found in a small crater at a depth of about 10 meters.
Like the Canyon Diablo meteorite in Arizona and the Odessa meteorite, it is classifed as a coarse octahedrite (siderite), nickel-iron meteorite.
It measures 95 x 62 x 5 mm and weighs 172 grams.
This specimen is polished and coated to prevent corrosion and shows nice longitudinal crytals.
Campo-del-Cielo-slice1-1605
The largest known piece of this meteorite weighed more than 32 tons! It is estimated to have fallen betwen 2,800 and 6,000 years ago in the Gran Chaco Gualambra desert about 500 miles west-northwest of Buenos Aires, Argentina.
It was first reported by Spanish missionaries in 1576. Estimates of the date of fall are made from charred tree remains found in a small crater at a depth of about 10 meters.
Like the Canyon Diablo meteorite in Arizona and the Odessa meteorite, it is classifed as a coarse octahedrite (siderite), nickel-iron meteorite.
It measures 51 x 76 x 4mm and weighs 87 grams.
This specimen is highly oxidized (from handling in the Meteorite Petting Zoo) but shows octahedral crystals and some silicate inclusions.
Campo-del-Cielo-1607
The largest known piece of this meteorite weighed more than 32 tons! It is estimated to have fallen betwen 2,800 and 6,000 years ago in the Gran Chaco Gualambra desert about 500 miles west-northwest of Buenos Aires, Argentina.
It was first reported by Spanish missionaries in 1576. Estimates of the date of fall are made from charred tree remains found in a small crater at a depth of about 10 meters.
Like the Canyon Diablo meteorite in Arizona and the Odessa meteorite, it is classifed as a coarse octahedrite (siderite), nickel-iron meteorite.
This specimen is heavily regmaglypted (the thumbprint-sized depressions in the surface) but is not heavily oxidized. It is the most popular item in the Meteorite Petting Zoo because of its heft and the fact that it, well "looks like a meteorite!"
It measures 115 x 65 x 75 mm and weighs 1,282 grams (about 2 3/4 pounds).
Gibeon-side2-widmanstatten-1604
A thin slice of an elongated, triangular-prism-shaped Gibeon meteorite from Great Namaqualand, Namibia, South Africa. The finds were first reported in 1836.
This fine octahedrite (siderite) nickel-iron meteorite is widely known for its equisite Widmanstatten patterns. These patterns are brought to light by first polishing the surface and then etching it with nitric acid, which dissolves silicates, sulfites, and other minerals to reveal the patterns. It is believed that the fineness of the lines and the angles between them indicate the time it took the nickel-iron crystals to form in the asteroid or planetoid's core from which these meteorites originate. Patterns as fine as these are believed to result from cooling times of at least several tens of millions to hundreds of millions of years.
This specimen shows some small inclusions, fusion crust on the edges, and some rusty fingerprintes from handling in the Meteorite Petting Zoo(!).
It measures 98 x 80 x 3 mm and weighs 101 grams.
Brenham-gemmy-frontlit-1621
A small thin section of the Brenham, Kansas, pallasite. This one weighs 22 grams. The largest stone from this fall, discovered by Steve Arnold in 2005, weighed about a ton.
Measures 4 x 28 x 45 mm.
It is lighted from the front with a ringlight flash here to show the nickel-iron matrix.
Native Americans smashed specimens of this large fall and used the metal for knives and arrow points. The olivine was often used for decoration.
Early immigrant settlers often broke plowshares on large stones from this fall and reported them as meteorites beginning in about 1892.
Campo-del-Cielo-1607
The largest known piece of this meteorite weighed more than 32 tons! It is estimated to have fallen betwen 2,800 and 6,000 years ago in the Gran Chaco Gualambra desert about 500 miles west-northwest of Buenos Aires, Argentina.
It was first reported by Spanish missionaries in 1576. Estimates of the date of fall are made from charred tree remains found in a small crater at a depth of about 10 meters.
Like the Canyon Diablo meteorite in Arizona and the Odessa meteorite, it is classifed as a coarse octahedrite (siderite), nickel-iron meteorite.
This specimen is heavily regmaglypted (the thumbprint-sized depressions in the surface) but is not heavily oxidized. It is the most popular item in the Meteorite Petting Zoo because of its heft and the fact that it, well "looks like a meteorite!"
It measures 115 x 65 x 75 mm and weighs 1,282 grams (about 2 3/4 pounds).
Gibeon-side2-widmanstatten-1604
A thin slice of an elongated, triangular-prism-shaped Gibeon meteorite from Great Namaqualand, Namibia, South Africa. The finds were first reported in 1836.
This fine octahedrite (siderite) nickel-iron meteorite is widely known for its equisite Widmanstatten patterns. These patterns are brought to light by first polishing the surface and then etching it with nitric acid, which dissolves silicates, sulfites, and other minerals to reveal the patterns. It is believed that the fineness of the lines and the angles between them indicate the time it took the nickel-iron crystals to form in the asteroid or planetoid's core from which these meteorites originate. Patterns as fine as these are believed to result from cooling times of at least several tens of millions to hundreds of millions of years.
This specimen shows some small inclusions, fusion crust on the edges, and some rusty fingerprintes from handling in the Meteorite Petting Zoo(!).
It measures 98 x 80 x 3 mm and weighs 101 grams.
Brenham-gemmy-frontlit-1621
A small thin section of the Brenham, Kansas, pallasite. This one weighs 22 grams. The largest stone from this fall, discovered by Steve Arnold in 2005, weighed about a ton.
Measures 4 x 28 x 45 mm.
It is lighted from the front with a ringlight flash here to show the nickel-iron matrix.
Native Americans smashed specimens of this large fall and used the metal for knives and arrow points. The olivine was often used for decoration.
Early immigrant settlers often broke plowshares on large stones from this fall and reported them as meteorites beginning in about 1892.
A 294.4-gram stone from the Wolfe Creek, Western Australia fall.
Measures 64 x 63 x 45 mm (about the size of a golf ball).
Lots of iron, with surface rust. Some fusion crust showing on one of the views. Fairly brittle.
Classified as type III-B iron shale.
Measures 64 x 63 x 45 mm (about the size of a golf ball).
Lots of iron, with surface rust. Some fusion crust showing on one of the views. Fairly brittle.
Classified as type III-B iron shale.
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