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46-466: Kīlauea Iki is a pit crater that is next to the main summit caldera of Kīlauea on the island of Hawaiʻi in the Hawaiian Islands . It is known for its eruption in 1959 that started on November 14 and ended on December 20, producing lava fountaining up to 1900 feet and a lava lake in the crater. Today, the surface of the lava lake has cooled and it is now a popular hiking destination to view

92-423: A spinel -like structure similar to magnetite but uses one quadrivalent and two divalent cations M 2 M O 4 instead of two trivalent and one divalent cations. Olivine is named for its typically olive-green color, thought to be a result of traces of nickel , though it may alter to a reddish color from the oxidation of iron. Translucent olivine is sometimes used as a gemstone called peridot ( péridot ,

138-454: A subsidence crater or collapse crater ) is a depression formed by a sinking or collapse of the surface lying above a void or empty chamber, rather than by the eruption of a volcano or lava vent . Pit craters are found on Mercury , Venus , Earth , Mars , and the Moon . Pit craters are often found in a series of aligned or offset chains and in these cases, the features is called

184-495: A cheap way to sequester CO 2 . The presence of iddingsite on Mars would suggest that liquid water once existed there, and might enable scientists to determine when there was last liquid water on the planet. Because of its rapid weathering, olivine is rarely found in sedimentary rock . Norway is the main source of olivine in Europe, particularly in an area stretching from Åheim to Tafjord , and from Hornindal to Flemsøy in

230-521: A deep funnel-shaped pit. This pit filled with lava and for 19 years burned continuously, becoming famous as the Hawaiian Fire Pit. In 1924 the lava lake emptied when the walls of the crater cracked and collapsed and filled with water that turned to steam. After a week and a half Halema'uma'u had widened and was 1,700 feet deep. Rocks that were blasted away from the crater can still be seen on the caldera floor. Devil's Throat (pictured at right)

276-494: A discontinuous increase in the density of the Earth's mantle that can be observed by seismic methods. They are also thought to influence the dynamics of mantle convection in that the exothermic transitions reinforce flow across the phase boundary, whereas the endothermic reaction hampers it. The pressure at which these phase transitions occur depends on temperature and iron content. At 800 °C (1,070 K; 1,470 °F),

322-428: A high ratio of CaO to MgO. Subsequent eruption episodes produced samples that were a mixture of the two variants plus some additional amount of olivine . The reason for two different magma compositions may be two magma storage areas beneath Kilauea Iki that had higher olivine concentrations at the bottom. At the beginning of the eruption, both magma sources provided material to the surface, while later eruption episodes at

368-471: A lava lake and then draining back below ground. During the Kilauea Iki eruption, the level of the lava lake would rise until it reached the erupting vent partway up the crater wall, where lava drainback would begin. The first episode had 31 million cubic meters of lava flow into Kīlauea Iki with 1 million cubic meters draining back. During the following episodes, a total of 71 million cubic meters of lava

414-401: A mile or less in diameter. The term "pit crater" was coined by C. Wilkes in 1845 to describe craters along Hawaii's East Rift Zone. Hawaii is known for its volcanoes and pit craters. In 1868 an eyewitness saw more than two-thirds of the basin of Kilauea cave in and fill with a lava lake . This process happened repeatedly. The modern Halema'uma'u Shield began growing and then collapsed into

460-400: A pit crater chain. Pit crater chains are distinguished from catenae or crater chains by their origin. When adjoining walls between pits in a pit crater chain collapse, they become troughs . In these cases, the craters may merge into a linear alignment and are commonly found along extensional structures such as fractures, fissures and graben. Pit craters usually lack an elevated rim as well as

506-417: A shallow caldera ) or when the ceiling over a void is not solid enough to prevent collapse of the overlying material. Pit craters can also result from collapse of lava tubes or dikes , or from collapsed magma chambers under loose material. A newly formed pit crater has steep overhanging sides and is shaped inside like an inverted cone, growing wider closer to the bottom. Over time the overhangs fall into

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552-467: A surface dominated by olivine. The spectral signature of olivine has been seen in the dust disks around young stars. The tails of comets (which formed from the dust disk around the young Sun ) often have the spectral signature of olivine, and the presence of olivine was verified in samples of a comet from the Stardust spacecraft in 2006. Comet-like (magnesium-rich) olivine has also been detected in

598-479: A swarm of earthquakes in mid-August 1959 led to resumption of rapid swelling that continued until the eruption in November. Most of these earthquake swarms were at a depth of 40-60 km and likely related to upward magma movement from the mantle. By early November, more than 1,000 earthquakes were being recorded each day and tiltmeter measurements indicated swelling 3 times faster than previous rates. Lava fountaining

644-536: A thin layer of basalt. This eruption was preceded by the great Ka'ü earthquake of 1868 , a magnitude 7.9 earthquake that caused extensive damage on the island and resulted in collapses of the wall in Kilauea's summit caldera, withdrawal of lava from the summit caldera, and the brief eruption in Kilauea Iki. At 8:08 pm on November 14, 1959, an eruption began at the summit of Kilauea in the Kilauea Iki crater after several months of increased seismicity and deformation. Over

690-468: Is a magnesium iron silicate with the chemical formula ( Mg , Fe ) 2 Si O 4 . 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. Olivine has many uses, such as the gemstone peridot (or chrysolite), as well as industrial applications like metalworking processes. The ratio of magnesium to iron varies between

736-399: Is another good Hawaiian example of a pit crater, especially since we were able to observe its formation through collapse over time. It was first documented by Thomas Jaggar who estimated its dimensions as 15m x 10.5m x 75m. In 1923 William Sinclair was lowered into Devil's Throat on a rope. He found a cavern shaped like an upside down funnel which widened as he approached the bottom. He measured

782-496: Is characteristic of Hawaiian eruptions and the 1959 eruption of Kilauea Iki produced some of the highest lava fountains ever observed in Hawaii. At the beginning of the eruption, the fountain height was only 30 m, but this increased over the next several days to between 200 and 300 m. On November 21, the fountain went from 210 meters tall to a few gas bubbles in less than 40 seconds. Some of the fountains were extraordinarily high, with

828-407: Is much lower – about 1,200 °C (2,190 °F). Melting temperature varies smoothly between the two endmembers, as do other properties. Olivine incorporates only minor amounts of elements other than oxygen (O), silicon (Si), magnesium (Mg) and iron (Fe). Manganese (Mn) and nickel (Ni) commonly are the additional elements present in highest concentrations. Olivine gives its name to

874-508: Is no longer stable. Below depths of about 410 km (250 mi) olivine undergoes an exothermic phase transition to the sorosilicate , wadsleyite and, at about 520 km (320 mi) depth, wadsleyite transforms exothermically into ringwoodite , which has the spinel structure. At a depth of about 660 km (410 mi), ringwoodite decomposes into silicate perovskite ( (Mg,Fe)SiO 3 ) and ferropericlase ( (Mg,Fe)O ) in an endothermic reaction. These phase transitions lead to

920-477: Is reflected in several local names with "red" such as Raudbergvik (Red rock bay) or Raudnakken (Red ridge). Hans Strøm in 1766 described the olivine's typical red color on the surface and the blue color within. Strøm wrote that in Norddal district large quantities of olivine were broken from the bedrock and used as sharpening stones . Kallskaret near Tafjord is a nature reserve with olivine. Olivine

966-486: Is rich in magnesium and low in silica . That magma crystallizes to mafic rocks such as gabbro and basalt . Ultramafic rocks usually contain substantial olivine, and those with an olivine content of over 40% are described as peridotites . Dunite has an olivine content of over 90% and is likely a cumulate formed by olivine crystallizing and settling out of magma or a vein mineral lining magma conduits. Olivine and high pressure structural variants constitute over 50% of

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1012-416: Is stable to pressures equivalent to a depth of about 410 km (250 mi) within Earth. Because it is thought to be the most abundant mineral in Earth's mantle at shallower depths, the properties of olivine have a dominant influence upon the rheology of that part of Earth and hence upon the solid flow that drives plate tectonics . Experiments have documented that olivine at high pressures (12  GPa ,

1058-466: Is unique to Norway. It is rare and found on dry olivine ridges in the fjord districts of Sunnmøre and Nordfjord. Mg-rich olivine has also been discovered in meteorites , on the Moon and Mars , falling into infant stars, as well as on asteroid 25143 Itokawa . Such meteorites include chondrites , collections of debris from the early Solar System ; and pallasites , mixes of iron-nickel and olivine. The rare A-type asteroids are suspected to have

1104-558: Is used as a substitute for dolomite in steel works. The aluminium foundry industry uses olivine sand to cast objects in aluminium. Olivine sand requires less water than silica sands while still holding the mold together during handling and pouring of the metal. Less water means less gas (steam) to vent from the mold as metal is poured into the mold. In Finland, olivine is marketed as an ideal rock for sauna stoves because of its comparatively high density and resistance to weathering under repeated heating and cooling. Gem-quality olivine

1150-696: The French word for olivine). It is also called chrysolite (or chrysolithe , from the Greek words for gold and stone), though this name is now rarely used in the English language. Some of the finest gem-quality olivine has been obtained from a body of mantle rocks on Zabargad Island in the Red Sea . Olivine occurs in both mafic and ultramafic igneous rocks and as a primary mineral in certain metamorphic rocks . Mg-rich olivine crystallizes from magma that

1196-737: The Sunnmøre district. There is also olivine in Eid municipality. About 50% of the world's olivine for industrial use is produced in Norway. At Svarthammaren in Norddal olivine was mined from around 1920 to 1979, with a daily output up to 600 metric tons. Olivine was also obtained from the construction site of the hydro power stations in Tafjord. At Robbervika in Norddal municipality an open-pit mine has been in operation since 1984. The characteristic red color

1242-402: The planetesimal belt around the star Beta Pictoris . Minerals in the olivine group crystallize in the orthorhombic system ( space group P bnm ) with isolated silicate tetrahedra, meaning that olivine is a nesosilicate . The structure can be described as a hexagonal, close-packed array of oxygen ions with half of the octahedral sites occupied with magnesium or iron ions and one-eighth of

1288-418: The 15th episode producing a fountain reaching nearly 580 m (1,900 ft), among the highest ever recorded . After the end of each eruption episode, lava drained back into the vent which may have acted as a coolant for the underlying material, resulting in the triggering of the next episode of lava fountaining. Lava drainback is common during eruptions at Kilauea and occurs when magma erupts at the surface, forming

1334-655: The Earth's upper mantle, and olivine is one of the Earth's most common minerals by volume. The metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content also produces Mg-rich olivine, or forsterite . Fe-rich olivine fayalite is relatively much less common, but it occurs in igneous rocks in small amounts in rare granites and rhyolites , and extremely Fe-rich olivine can exist stably with quartz and tridymite . In contrast, Mg-rich olivine does not occur stably with silica minerals, as it would react with them to form orthopyroxene ( (Mg,Fe) 2 Si 2 O 6 ). Mg-rich olivine

1380-402: The aftermath of an eruption. Lava tubes associated with Kīlauea Iki are responsible for the vast ʻAilāʻau eruption , carbon 14 dated from c.  1445 and erupting continuously for approximately 50 years, which blanketed much of what is now Puna District with 5.2 ± 0.8 km of basalt lava. Kilauea Iki experienced a minor eruption in 1868, which covered the floor of the crater in

1426-413: The crater. The trail crosses the floor of the crater, which once was a lake of lava . Even after 50 years, the parts of the surface are still warm to the touch. Rainwater seeps into the cracks and makes contact with the extremely hot rock below and steam is emitted from various surface cracks. The steam and some rocks are hot enough to cause serious burns. Pit crater A pit crater (also called

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1472-438: The ejecta deposits and lava flows that are associated with impact craters . Pit craters are characterized by vertical walls that are often full of fissures and vents. They usually have nearly circular openings. As distinct from impact craters, these craters are not formed from the clashing of bodies or projectiles from space. Rather, they can be formed by a lava explosion from a bottled up volcano (the explosion leaving

1518-415: The end of the 8th episode, the lava lake formed in the crater reached its greatest volume (58 million cubic yards) and depth (414 feet). The final volume and depth of the lava lake after the end of the eruption on December 20 was approximately 50 million cubic yards and 365 feet, respectively. In 1988, a drilling project of Kilauea Iki showed that the lava lake depth was deeper than expected by 50-90 feet. This

1564-591: The floor as about 60m in diameter and the crater's depth around 78m. The crater's mouth widened over time and in 2006 the crater's dimensions were measured as 50m x 42m x 49m. This growth is explained by observing pieces of the overhanging roof breaking off and falling to the bottom. These shards gradually piled up on the crater floor, reducing its depth. The process also happens on the surface of Mars and other terrestrial planets. Features resembling pit craters have been observed on Mercury . Olivine The mineral olivine ( / ˈ ɒ l . ɪ ˌ v iː n / )

1610-550: The group of minerals with a related structure (the olivine group ) – which includes tephroite ( Mn 2 SiO 4 ), monticellite ( Ca MgSiO 4 ), larnite (Ca 2 SiO 4 ) and kirschsteinite (CaFeSiO 4 ) (commonly also spelled kirschteinite ). Olivine's crystal structure incorporates aspects of the orthorhombic P Bravais lattice , which arise from each silica (SiO 4 ) unit being joined by metal divalent cations with each oxygen in SiO 4 bound to three metal ions. It has

1656-419: The lava lake during each eruption episode . During lava drainbacks, a giant counter-clockwise whirlpool would form . Samples collected from the first episode of the eruption were composed of two different kinds of magma. The first variant was identical to previous magmas erupted in the 1954 Kilauea caldera eruption and the second variant had a composition different from anything seen at previous eruptions, with

1702-493: The next month, the crater experienced 17 eruption episodes, each one (except for the last) beginning with lava fountaining and ending with lava drainback. After the first episode, which lasted 7 days, most of the remaining episodes were less than 24 hours, with the shortest (14th episode) lasting less than 2 hours. Volcanic ejecta from the main fissure on the western side of the crater formed the 70 meter high Pu'u Pua'i tephra cone (Hawaiian for 'gushing hill'). On December 11, 1959, at

1748-399: The pit and the crater fills with talus from the collapsing sides and roof. A middle-aged pit crater is cylindrical but its rim will continue to collapse, resulting in the crater's expanding outward until it resembles a funnel or drain—narrower at the bottom than the top. While pit craters and calderas form through similar processes, the former term is usually reserved for smaller features of

1794-404: The pressure at depths of about 360 km (220 mi)) can contain at least as much as about 8900 parts per million (weight) of water, and that such water content drastically reduces the resistance of olivine to solid flow. Moreover, because olivine is so abundant, more water may be dissolved in olivine of the mantle than is contained in Earth's oceans. Olivine pine forest (a plant community )

1840-577: The pure magnesium end member, forsterite, transforms to wadsleyite at 11.8 gigapascals (116,000  atm ) and to ringwoodite at pressures above 14 GPa (138,000 atm). Increasing the iron content decreases the pressure of the phase transition and narrows the wadsleyite stability field. At about 0.8 mole fraction fayalite, olivine transforms directly to ringwoodite over the pressure range 10.0 to 11.5 GPa (99,000–113,000 atm). Fayalite transforms to Fe 2 SiO 4 spinel at pressures below 5 GPa (49,000 atm). Increasing

1886-407: The single vent on the west side of the caldera contained a mixture of the two magmas. Additionally, the later eruption episodes were sourced from deeper sections of the magma chambers, resulting in higher concentrations of olivine. Drivers may view Kīlauea Iki from either a lookout point or the trailhead parking lot. Guests can hike across Kīlauea Iki by descending from Byron Ledge , which overlooks

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1932-491: The temperature increases the pressure of these phase transitions. Olivine is one of the less stable common minerals on the surface according to the Goldich dissolution series . It alters into iddingsite (a combination of clay minerals, iron oxides and ferrihydrite ) readily in the presence of water. Artificially increasing the weathering rate of olivine, e.g. by dispersing fine-grained olivine on beaches, has been proposed as

1978-408: The tetrahedral sites occupied by silicon ions. There are three distinct oxygen sites (marked O1, O2 and O3 in figure 1), two distinct metal sites (M1 and M2) and only one distinct silicon site. O1, O2, M2 and Si all lie on mirror planes , while M1 exists on an inversion center. O3 lies in a general position. At the high temperatures and pressures found at depth within the Earth the olivine structure

2024-486: The two endmembers of the solid solution series: forsterite (Mg-endmember: Mg 2 Si O 4 ) and fayalite (Fe-endmember: Fe 2 Si O 4 ). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and/or fayalite (Fa) ( e.g. , Fo 70 Fa 30 , or just Fo 70 with Fa 30 implied). Forsterite's melting temperature is unusually high at atmospheric pressure, almost 1,900 °C (3,450 °F), while fayalite's

2070-460: Was ejected during a month-long eruption that stopped on December 20, 1959. Only 8 million cubic meters of lava remained, with 63 million cubic meters of lava draining back into the Kīlauea magma reservoir. Often the lava drainback had a higher rate of flow than the eruptions. With every filling and draining of the lava lake, a 'black ledge' was formed along the rim of the crater which marked the level of

2116-489: Was likely due to the crater floor collapsing during the 1959 eruption. Early warning signs of the impending eruption included outward tilting at the summit region and increased seismicity. Tiltmeter measurements between November 1957 and February 1959 indicated that magma was migrating towards the summit, causing swelling of the ground surface. Swelling ceased and deflation of the summit began after several earthquakes occurred on February 19, 1959. Slow deflation continued until

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