Why is breccia common on the moon

Most of the dark clast are impact-melt breccias or glassy shards. A few glass spherules and are evident. Agglutinates are hard to find in regolith breccias and there may be none in this section.

Sample is a very friable regolith breccia. It breaks apart easily and the clasts are easy to remove. I have done it. I think that it would not survive lunar ejection and terrestrial capture as a lunar meteorite. In contrast, regolith breccia below is very coherent. Lunar meteorite NWA is a fragmental breccia.

We are looking at a sawn slice. Again, note that the clasts are shades of gray, not brightly colored. Also, there are several different kinds colors and textures of clasts, which we would expect in a lunar regolith or fragmental breccia considering the diversity of rocks in the Apollo 11 and 16 regolith samples above.

In contrast, many terrestrial sedimentary rocks and basalts contain of clasts or phenocrysts of a single rock or mineral type. Origin of Anorthosite The ancient crust of the Moon is believed to have been composed of the rock, anorthosite, a calcium-rich white rock. Apollo 16 Landing Site. Lunar Anorthosite Surface Sample.

Lunar Anorthosite Sample. Crisium Basin The Crisium basin, about kilometers miles in diameter is one of many large circular lunar depressions. Crater Lambert This crater in Mare Imbrium, 32 kilometers 20 miles in diameter, is surrounded by a blanket of material blasted out by the impact that produced the crater. Secondary Craters Rocks thrown out during the formation of large impact craters often produce smaller, secondary craters when they fall back to the lunar surface.

Zap Pit Tiny impact craters, called "zap pits" are produced by small, high velocity particles and are common on the exposed faces of lunar rocks. Breccia in Breccia Some rock fragments found in breccias are pieces of more ancient breccias. Granulation A common feature of many lunar crystalline rocks is the grinding and crushing, or granulation, of their minerals caused by repeated meteoric bombardment.

Apollo 17 Landing Site. Lunar Breccia Surface Sample. Lunar Breccia Sample. It bounced upon landing, leaving the footprint. Television images of the footprint were transmitted to Earth, showing us that men would be able to move about without sinking deep into the soil. Armstrong left this bootprint in the lunar soil at Tranquillity Base, July 20, The impression, about 2. Lunar Roving Vehicle Tracks The lunar roving vehicle, driven by astronauts on the moon, left these tracks.

Studies of the wheels' performance and the tracks they left have improved understanding of the mechanical properties of lunar soil. Orange Soil Apollo 17 astronauts discovered an area of orange soil on the rim of Shorty crater, in the Valley of Taurus-Littrow.

Soil Particles Lunar soil contains fragments of the major lunar rock types: basalt A , anorthosite B , and breccia C.

Soil Texture The texture of undisturbed lunar soil can be seen in this close-up photograph, which shows the soil enlarged about 35 times.

Green Class Most lunar glassy materials were created by the shock of meteoroid impacts. Orange Glass Orange glass spheres, like the green glass spheres, originated in lava fountains. Apollo Schmitt on Moon. Apollo 17 Lunar Soil. These rocks can be 4.

Regolith is the loose, dusty soil that covers the Moon's surface up to a few meters on the Mare and sometimes triple that on the Highlands. It exists due to the Moon's constant bombardment with meteors - as the first line of defense, what might be larger rocks are ground into a powder upon these impacts. The composition of the Regolith mirrors that of the rocks underneath, which means the soil is mostly basalt on the the Mare and largely Highland rock on the Highlands.

What rock types are most common on the moon? Becca M. Feb 4, Breccia: Shocked Rock Breccia are composite rocks formed from jagged and irregularly-shaped fragments that melted and then fused together during a meteoric collision. We have chemically tested several such rocks and none has been a Moon rock. Other people suspect that they have found a lunar meteorite. None of the many samples that we have been sent has been a lunar meteorite, except those from meteorite dealers, those persons who bought lunar meteorites from a dealer, or those from experienced meteorite prospectors who found them in the deserts of northern Africa or Oman.

It weighed 23 grams, just less than an ounce. The cube is 1 cm on each side. They undoubtedly exist, but the probability of finding a lunar meteorite in a temperate environment is incredibly low. Many experienced meteorite collectors have been looking and none have yet succeeded.

Realistically, the probability that an amateur will find a lunar meteorite is so low that I cannot raise much enthusiasm to examine the thousands of rocks and photos that I have been asked to examine. If I wanted to find a lunar meteorite myself, I would not scour the Mojave Desert. I would look through rock collections at colleges and universities. It is not unreasonable that a lunar meteorite exists in an old drawer somewhere because a sharp-eyed geology student or professor found a funny-looking rock years ago in a place it did not belong.

It would be easy to overlook a lunar meteorite. A weathered lunar meteorite would look remarkably unremarkable. Weathered pebbles of lunar meteorite Northwest Africa , 1-cm cube on right. If I found a few of these in my driveway, I would not give them a second look.

Photo credit: Rob Wesel Here I discuss some aspects of lunar geology, mineralogy, and chemistry that guide us in our attempts to identify lunar material. Material at the lunar surface contains a high proportion of non-crystalline material, but most of this material is glass that formed from melting of rocks containing the four major minerals.

Many other minerals have been identified, but most are rare and occur only as very small grains interstitial to the four major minerals and cannot be seen with the naked eye. Some of the most common minerals at the surface of the Earth are rare or have never been found in lunar samples.