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Troctolite 76535
Troctolite 76535 is a lunar sample discovered and collected on the Apollo 17 mission in 1972 in the Taurus–Littrow valley. It has a mass of about and is about across at its widest point. It was collected by geologist astronaut Harrison Schmitt as part of a "rake sample" of lunar soil at Geology Station 6, near the base of the North Massif. Troctolite 76535 has been called the most interesting sample returned from the Moon. Description Troctolite 76535 is a coarse-grained plutonic rock that is believed to have had a slow cooling history. The rock originates from early in the Moon's history. Geologists have described it as a coarse-grained olivine-plagioclase cumulate with a granular polygonal texture. Olivine and plagioclase are of about equal quantities within 76535, while the remaining approximately 4% is made up of primarily orthopyroxene. According to early studies, the sample cooled at a depth of about , as well as its reequilibration and annealing. Later work indicated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthopyroxene
The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) or magnesium (Mg) and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium (Cr), aluminium (Al), magnesium (Mg), cobalt (Co), manganese (Mn), scandium (Sc), titanium (Ti), vanadium (V) or even iron (Fe II) or (Fe III). Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a common structure consisting of single chains of silica tetrahedra. Pyroxenes that crystallize in the monoclinic system are known as clinopyroxenes and those that crystallize in the orthorhombic system are known as orthopyroxenes. The name ''pyroxene'' is derived from the Ancient Greek words for 'fire' ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Science
Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior to the Fire'' * Lunars, a fictional race in the series ''The Lunar Chronicles'' by Marissa Meyer Other uses * Lunar Magic, Super Mario World level editor * Lunar Design, or LUNAR, a San Francisco-based design consultancy * Hasselblad Lunar, a digital camera * Lunar, a brandname of Ethinylestradiol/cyproterone acetate, a birth control pill * Lunar C (Jake Brook, born 1990), English rapper See also * * * Lunar calendar, based upon the monthly cycles of the Moon's phase ** Lunar day, in such calendars ** Lunar month, in such calendars * Moon (other) * Luna (other) Luna commonly refers to: * Earth's Moon, named "Luna" in Latin * Luna (goddess), the ancient Roman personification of the Moon Luna may also refer to: Places ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonic Rocks
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusion, such as a volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grained plutonic rock (typically formed deeper in the Earth's crust in batholiths or stocks) a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamo Theory
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can maintain a magnetic field over astronomical time scales. A dynamo is thought to be the source of the Earth's magnetic field and the magnetic fields of Mercury and the Jovian planets. History of theory When William Gilbert published ''de Magnete'' in 1600, he concluded that the Earth is magnetic and proposed the first hypothesis for the origin of this magnetism: permanent magnetism such as that found in lodestone. In 1919, Joseph Larmor proposed that a dynamo might be generating the field. However, even after he advanced his hypothesis, some prominent scientists advanced alternative explanations. Einstein believed that there might be an asymmetry between the charges of the electron and proton so that the Earth's magnetic field would ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Core
A planetary core consists of the innermost layers of a planet. Cores may be entirely solid or entirely liquid, or a mixture of solid and liquid layers as is the case in the Earth. In the Solar System, core sizes range from about 20% (the Moon) to 85% of a planet's radius (Mercury). Gas giants also have cores, though the composition of these are still a matter of debate and range in possible composition from traditional stony/iron, to ice or to fluid metallic hydrogen. Gas giant cores are proportionally much smaller than those of terrestrial planets, though they can be considerably larger than the Earth's nevertheless; Jupiter's is 10–30 times heavier than Earth, and exoplanet HD149026 b may have a core 100 times the mass of the Earth. Planetary cores are challenging to study because they are impossible to reach by drill and there are almost no samples that are definitively from the core. Thus, they are studied via indirect techniques such as seismology, mineral physics, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermochronology
Thermochronology is the study of the thermal evolution of a region of a planet. Thermochronologists use radiometric dating along with the closure temperatures that represent the temperature of the mineral being studied at the time given by the date recorded to understand the thermal history of a specific rock, mineral, or geologic unit. It is a subfield within geology, and is closely associated with geochronology. A typical thermochronological study will involve the dates of a number of rock samples from different areas in a region, often from a vertical transect along a steep canyon, cliff face, or slope. These samples are then dated. With some knowledge of the subsurface thermal structure, these dates are translated into depths and times at which that particular sample was at the mineral's closure temperature. If the rock is today at the surface, this process gives the exhumation rate of the rock. Common isotopic systems used for thermochronology include fission track dating in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulate
Cumulate rocks are igneous rocks formed by the accumulation of crystals from a magma either by settling or floating. Cumulate rocks are named according to their texture; cumulate texture is diagnostic of the conditions of formation of this group of igneous rocks. Cumulates can be deposited on top of other older cumulates of different composition and colour, typically giving the cumulate rock a layered or banded appearance. Formation Cumulate rocks are the typical product of precipitation of solid crystals from a fractionating magma chamber. These accumulations typically occur on the floor of the magma chamber, although they are possible on the roofs if anorthite plagioclase is able to float free of a denser mafic melt. Cumulates are typically found in ultramafic intrusions, in the base of large ultramafic lava tubes in komatiite and magnesium rich basalt flows and also in some granitic intrusions. Terminology Cumulates are named according to their dominant mineralogy and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Crust
Having a mean density of 3,346.4 kg/m3, the Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and planetary core. This structure is believed to have resulted from the fractional crystallization of a magma ocean shortly after its formation about 4.5 billion years ago. The energy required to melt the outer portion of the Moon is commonly attributed to a giant impact event that is postulated to have formed the Earth-Moon system, and the subsequent reaccretion of material in Earth orbit. Crystallization of this magma ocean would have given rise to a mafic mantle and a plagioclase-rich crust. Geochemical mapping from orbit implies that the crust of the Moon is largely anorthositic in composition, consistent with the magma ocean hypothesis. In terms of elements, the lunar crust is composed primarily of oxygen, silicon, magnesium, iron, calcium, and aluminium, but important minor and trace elements such as titanium, uranium, thorium, pota ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plagioclase
Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi3O8 to CaAl2Si2O8), where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or 'record-groove' effect. Plagioclase is a major constituent mineral in the Earth's crust, and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolution of igneous rocks. Plagioclase is also a major constituent of rock in the highlan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Sample
Moon rock or lunar rock is rock originating from Earth's Moon. This includes lunar material collected during the course of human exploration of the Moon, and rock that has been ejected naturally from the Moon's surface and landed on Earth as meteorites. Sources Moon rocks on Earth come from four sources: those collected by six United States Apollo program crewed lunar landings from 1969 to 1972; those collected by three Soviet uncrewed Luna probes in the 1970s; those collected by the Chinese Lunar Exploration Program's uncrewed probes; and rocks that were ejected naturally from the lunar surface before falling to Earth as lunar meteorites. Apollo program Six Apollo missions collected 2,200 samples of material weighing , processed into more than 110,000 individually cataloged samples. Luna program Three Luna spacecraft returned with of samples. The Soviet Union abandoned its attempts at a crewed lunar program in the 1970s, but succeeded in landing three robotic Luna s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. For this reason, olivine has been proposed as a good candidate for accelerated weathering to sequester carbon dioxide from the Earth's oceans and atmosphere, as part of climate change mitigation. Olivine also has many other historical uses, such as the gemstone peridot (or chrysolite), as well as industrial applications like metalworking processes. The ratio of magnesium to iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember: ) and fayalite (Fe-endmember: ). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and fayalite (Fa) (''e.g.'', Fo70Fa30). Forsterite's melting temperature is unusually high at atmospheric pressure, almost , while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_Stillwater_Mine_MT.jpg "Click for more on -> Cumulate")
