Solar nebula refractory metal (W, Re, Os, Ir, Mo, Ru, Pt, and Rh) with high vaporization temperatures in excess of ~1620K were the first solids to condense as a single alloy near the midplane of the hot, primordial, pre-stellar core outward to ~3 AU during the rapid infall stage (Class 0–I) which began over 4.568 b.y. ago (Liffman et al., 2012). These first metal condensates are now present within sub-micron-sized refractory metal nuggets, which likely formed as precipitates of a silicate liquid during rapid quenching (~ 700–1000°C/40 s) under reducing conditions (Schwander et al., 2015). Thereafter, these metal nuggets might have served as nucleation sites for later phases such as spinel or melilite, minerals that became major constituents of CAIs. Solar refractory metal nuggets also occur as large, isolated opaque assemblages contained in primitive carbonaceous meteorites, initially referred to as Fremdlinge, while presolar refractory metal nuggets have been discovered hosted in presolar graphite grains in primitive meteorites. These are thought to be primary condensate assemblages following Type II supernovae and low-metallicity AGB stars, where metallicity is based on the proportion of elements heavier than helium (Croat et al., 2013). The solar nebula refractory metal nuggets are thought to have formed relatively fast (~100 years) during an interval of ~100,000 years, at a temperature of 1440–1616K and a pressure of 100 dyne/cm²; these conditions were created during periods of low accretion by the proto-Sun (Schwander et al., 2011).

Condensation of other refractory phases (oxides and silicates with vaporization temperatures in excess of ~1350K) followed. In regions of solar composition, mineral condensation is predicted to have progressed in the following sequence: corundum ⇒ hibonite ⇒ grossite ⇒ perovskite ⇒ melilite ⇒ spinel ⇒ diopside ⇒ forsterite ⇒ enstatite. This equilibrium condensation sequence is most closely exemplified in refractory inclusion 31-2 in the CO3.00 chondrite DOM 08006 (Simon et al., 2019). A different sequence was predicted by Manga et al. (2019) based on density functional theory applied to the pyroxene solid-solution series. They contend that the first phase to condense would be cubic perovskite at temperatures of 1682–1637K, followed by an Al-Ti-rich pyroxene phase (CaTiAl2O6) at ~1670K. Similarly, Han et al. (2019) analyzed zoned CAIs from Efremovka and TIL 07003/7 and observed that perovskite was the first phase to condense, possibly attesting to rapid cooling beyond the corundum condensation point.

standby for phase relations photo standby for phase relations photo
Condensation phase relations at various temperatures, pressures, and gas:dust ratios
Photo credit: Ebel, D. S. (2006), Condensation of rocky material in astrophysical environments.
In Meteorites and the Early Solar System II, D. Lauretta et al., editors.
University of Arizona in Tucson. pp. 253–277, + four color plates (after plates 1 and 4).

The condensation of these refractory minerals and the formation of calcium–aluminum-rich inclusions (CAIs) occurred episodically during the time interval between ~40 t.y. and ~160 t.y. after the beginning of the rapid infall stage (Pignatale et al., 2019 and references therein); CAI formation was further constrained by Pignatale et al. (2018) to within the first 80 t.y. of the molecular cloud collapse to account for CAI delivery to the outer CC region of the disk by viscous expansion. By analyzing only the Mo isotope variability in CAIs that is associated with the rapid neutron capture process of nucleosynthesis (r-process, quantified by Δ95Mo notation), Brennecka et al. (2020) determined that the timing of CAI formation corresponded to the Class I/II transition stage of protostellar evolution (see schematic diagram below). During this transition stage, infall from the molecular cloud evolved from a higher to lower abundance of r-process material (i.e., higher to lower Δ95Mo).

Schematic of the Early Evolution of the Solar System
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click on diagram for a magnified view

Schematic diagram credit: Brennecka et al., Science, vol. 370 p. 839 (2020)
'Astronomical context of Solar System formation from molybdenum isotopes in meteorite inclusions'

A precise age for CAI formation of 4.56730 (±0.00016) b.y. was obtained by Amelin et al. (2002, 2010) and Connelly et al. (2012). Older CAI ages (by 1.4 m.y.) were ascertained for a suite of chondrules and achondrites by Desch et al. (2022 #2567) through a more precise examination of the Al–Mg and Pb–Pb chronometry. By their statistical methodology, a CAI age (relative Solar System time = 0) of 4.56873 (±0.00016) b.y. was obtained. They attributed the discrepancies between the Al–Mg system and the Pb–Pb system to transient heating events which affected only the Pb–Pb chronometer.

Gaches et al. (2020) concluded that an external source for the 26Al enrichment in the protostellar disk would necessarily involve many unlikely chance occurrences. Instead, they presented an internal source model whereby enrichment of 26Al in the inner disk was attained through irradiation of the disk surface by high-energy (MeV) cosmic ray protons which had been accelerated in accretion shocks. The 26Al production efficiency is generally greatest with a lower accretion rate (≤10–8 M/yr) and a weaker protostellar magnetic field strength (thus a smaller magnetosonic radius favorable to cosmic ray acceleration). The production of 26Al was coeval with that of CAIs as the gas cooled below 1500 K during the protostellar Class I/II stage.

Schematic of 26Al Enrichment by Cosmic Ray Acceleration in Protostellar Accretion Shocks
standby for cosmic ray acceleration diagram
Schematic diagram credit: Gaches et al., The Astrophysical Journal, vol. 898, #1 (2020, open access link)
'Aluminum-26 Enrichment in the Surface of Protostellar Disks Due to Protostellar Cosmic Rays'

During this Class I/II transition stage of protostellar evolution, radiogenic 26Al would have been injected into the solar protoplanetary disk by one or more supernovae (Ciesla and Yang, 2010), or what is now considered more plausible, by a nearby Wolf-Rayet star. A number of independent chronometric studies (e.g., Budde et al., 2018) have demonstrated a concordance in Al–Mg and Hf–W ages for CV CAIs, CV chondrules, CR chondrules, and angrites (D'Orbigny and Sahara 99555), which attests to a homogeneous distribution of 26Al during the first ~4–5 m.y. of solar system history. A homogeneous distribution of 26Al was also supported by Desch et al. (2022 #2567 in their CAI dating analysis mentioned above, as well as in their chapter for Protostars and Planets VII (2022) titled 'Short-Lived Radionuclides in Meteorites and the Sun's Birth Environment'. In the latter work, they concluded that virtually all of the short-lived radionuclides present in meteorites were homogeneously distributed in the molecular cloud prior to the start of the Solar System, the abundances of which were the result of ongoing stellar nucleosynthesis within the Galactic host spiral arm.

At a heliocentric distance corresponding to the location at which CV- and CK-group carbonaceous chondrites were formed, highly porous, refractory, mm-to-cm-sized dustballs became concentrated with CAIs of similar mass forming 16O-rich accretionary rims (Rubin, 2011). Many of these refractory minerals, specifically those which formed within the initial 160,000 years (commensurate with the lifetime of class 0 protostars), survived (perhaps within planetesimals) as primary condensates of a dust-enhanced (10 × solar gas composition which was 16O-rich: Δ17O ~ –25‰ to –20‰; Simon et al., 2019) nebular gas having properties of variable but low pressure, variable but high temperature, and a reduced environment (conditions attested by volatility fractionated REEs). Episodic melting of these CAIs occurred over the next 300,000 years, with some experiencing remelting in the chondrule-forming region at least 900,000 years after initial formation (MacPherson et al., 2010).

Some of the earliest refractory phases (hibonite-bearing) formed prior to the incorporation and mixing of 26Al into the solar nebula and are present in CM chondrites (no resolvable 26Mg excesses; e.g., platy-crystals [PLACs] and blue aggregates [BAGs]), while others do show evidence of in situ 26Al decay (e.g., spinel–hibonite spherules [SHIBs] and CAIs). CAIs are likely the direct condensates or evaporative residues formed from one or more episodes of rapid heating and slow cooling of precursor dust. This process continued over a time span as short as 20–100 t.y. (consistent with an FU-Orionis outburst; see below) (Krot et al., 2009; Wurm and Haack, 2009 and references therein), which is datable by the Hf–W and U–Pb systems to 4.5685 (±0.0003) b.y. ago relative to the angrites D'Orbigny, NWA 4590, and NWA 4801 (Burkhardt et al., 2008; Nyquist et al., 2009). This age is in agreement with that obtained by Pb–Pb and Al–Mg dating methods for a CAI from the CV3 NWA 2364 of 4.5682 b.y. (Bouvier and Wadhwa, 2010). It was calculated that initial nebular condensation processes account for 80% of the refractory element enrichment (e.g. Ca, Al) in type A and type B CAIs, while 20% is due to the subsequent evaporation of more volatile elements (e.g. Mg, Si) (Grossman et al., 2008).

Evidence for an early, instantaneous, impact-generated shock wave origin for CAIs (and chondrules) around large planetesimals has been presented by Sanders (2008) and by Hood and Weidenschilling (2011). This would include an origin associated with bow shocks produced by planetesimal interactions with Jupiter, or more plausibly, an origin within shock zones associated with impact-generated vapor-melt plumes from high-velocity collisions of large planetesimals. Chondrules were melted and slowly cooled within the dusty zone of large planetesimals on a timescale that overlaps the formation of CAIs and which continued for ~2.6 m.y (commensurate with the lifetime of class 1–3 protostars). During that period, some CAIs were transported radially outward into the accretion zones of chondrite parent bodies. If employing the planetesimal nebular shock model, any delay between the formation of CAIs and chondrules may be explained as the time required for the completion of Jupiter's formation.

Following their formation near the proto-Sun, many of these refractory minerals were transported radially outward by turbulent diffusion mechanisms to chondritic accretionary regions. Calculations show that CAIs measuring up to 1 cm in size, representing a total mass of 0.005 Earth masses, could have been easily transported to the asteroid belt at a distance of ~3 AU, and some may have exceeded 10 AU. Here the condensation sequence was arrested, and these minerals remained stable against gas drag and the accretionary influence of the Sun for at least 1 m.y. Eventually, they rained down to the nebular midplane and coalesced with newly forming chondrules to form the nascent chondritic planetesimals.

Other CAIs may have been confined to the protoplanetary disk embedded in the center of spiral arms (Haghighipour and Boss, 2003), or possibly transported to cooler heliocentric regions (2–5 AU) by photophoresis—a force created in response to an ~100-fold increase in the Sun's luminosity during an FU-Orionis outburst resulting from an enhanced accretion rate within ~1 AU of the central star (Wurm and Haack, 2009). When cm-sized CAIs are fully illuminated in an optically thin region of the disk, they are transported vertically and radially outward along the surface of the (flared) protoplanetary disk following a temperature gradient from hot to cold.

Another hypothesis under consideration attributes the outward transport of CAIs to bipolar outflows (x-wind and/or disk winds). However, this magnetocentrifugal transport mechanism was thoughtfully investigated by Desch et al. (2021 #2663) and Herbst et al. (2021 #6272) and demonstrated to be invalid for all but the smallest CAIs. Their data, based on gravitational and other constraints, show that only CAIs with radii <1 µm can be lofted and accelerated long enough to reach the outer regions of the Solar nebula. At the same time, particles ≪1 µm may exceed escape velocity or remain bound to the outflow gas.

Very ancient ages have been measured for some iron meteorites and for the ungrouped basaltic meteorite Asuka 881394, with the latter having an age of 4.56675 (±0.00031) b.y. based on the 238U/235U ratio of 137.88, or 4.56557 (±0.00055) b.y. based on the newly refined 238U/235U ratio of 137.768 (±0.038) (Amelin et al., 2014; Wimpenny et al., 2013; Koefoed et al., 2015). These similar ancient ages indicate that their respective parent bodies accreted contemporaneously with CAI formation (Wadhwa et al., 2009).

Schematic of the Evolution of the Early Solar System
A. Giant Molecular Cloud ⇒ B. Protostars ⇒ C. Proto-Sun and Protoplanetary Disk
standby for solar system evolution schematic
click on diagram for a magnified view

Diagram credit: Van Kooten et al., PNAS, vol. 113, no. 8 (2016, open access link)
'Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites'

CAIs are particularly abundant in the CV-group of carbonaceous chondrites, but they also occur in many other carbonaceous chondrite groups, in K chondrites, in ordinary chondrites, and in enstatite chondrites, and they have been identified in comet samples (81P/Wild-2) from NASA's STARDUST mission. Wark–Lovering monomineralic rims commonly occur on most all CAI types, providing evidence of episodic flash heating events in a more oxidizing environment of the solar nebula; these energetic events are often cited as being associated with magnetic reconnection flares. These events resulted in volatilization of Mg, Si, and Ca from the outermost layer of CAIs, followed by the diffusion of elements (possibly derived from accetionary forsterite dust which is texturally and mineralogically similar to AOA forsterite) back onto the surface of the CAIs. Alternatively, the formation of Wark–Lovering rims may be attributed to relatively slow evaporation from solid CAIs. Additional information on CAI formation can be found on the Allende page.

Ebert et al. (2018) investigated the Ti isotope systematics of CAIs and Na–Al-rich chondrules from ordinary and CO chondrites. CAIs from both of these chondrite groups show the presence of nucleosynthetic anomalies, such as an average excess in ε50Ti of ~9. On the other hand, although Na–Al-rich chondrules in the CO chondrites studied have a ε50Ti excess, those from the ordinary chondrites do not. Given that Na–Al-rich chondrules from both CO and ordinary chondrites are considered to have incorporated refractory components (~30–80% CAIs and/or AOAs), they reason that the refractory material precursor to ordinary chondrules did not have a ε50Ti excess, and thus was different from the refractory material admixed to form CO chondrules. They contend that this difference may be due to the specific formation region of the respective precursor refractory material: either in the non-carbonaceous (NC) region within the inner Solar System (ordinary chondrites), or in the carbonaceous (CC) region beyond Jupiter (CO chondrites). They propose that the rare CAIs with ε50Ti excesses which are present in ordinary chondrites could represent the smaller-sized CAIs (<150 µm) that were able to migrate across Jupiter's gap in the protoplanetary disk (see diagram below).

Schematic of the Transportation and Distribution of CAIs in the Early Solar System
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click on photo for a magnified view

Diagram credit: Ebert et al., EPSL, vol. 498 p. 263 (2018)
'Ti isotopic evidence for a non-CAI refractory component in the inner Solar System'

CAIs were originally grouped as 'coarse-grained' and 'fine-grained' inclusions (Grossman, 1975). However, continued studies have led to further refinement in their classification, with an emphasis on those from the CV group. Coarse-grained CAIs have been classified into three main groups (A, B, and C) based primarily on the proportions of fassaite and melilite, the latter corresponding to the series with Ca-rich end member åkermanite and Al-rich end member gehlenite. Other characteristic phases include spinel, hibonite, perovskite, and anorthite.

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NWA 2086, CV3R, 46 g end section with large (the largest known?) CAI
Photo courtesy of Dr. Martin Horejsi
See the complete story of this CAI as published in Meteorite Times Magazine—The Accretion Desk.



  • nebular condensate origin with a multi-stage formation history
  • irregular-shaped with complex multi-layered or concentrically-zoned structure
  • in reduced CV chondrites they are composed primarily of spinel at their cores with melilite mantles, along with Al-diopside (or fassaite) and anorthite
  • in oxidized CV chondrites original minerals may be replaced by secondary nepheline and sodalite
  • melilite mostly altered to secondary phases such as andradite and grossular


  • olivine-rich objects present in most grouped and ungrouped carbonaceous chondrites, and have been found in an LL3.0 ordinary chondrite
  • the least refractory fine-grained inclusions
  • irregularly-shaped, mm- to cm-sized, porous or compact, sintered and annealed aggregates of high-temperature (~1200–1384K), 16O-rich, solar nebular condensates
  • originated by fractional condensation or fractional vaporization in an 16O-rich reservoir
  • rapid cooling occurred at an estimated rate of >0.02K/hr at a nebular pressure of 0.0001 bar
  • porous AOA olivines contain low CaO and high MnO and CrO concentrations indicative of rapid condensation and agglomeration of nebular forsterite through disequilibrium processes
  • compact AOA olivines contain higher CaO and lower MnO and CrO concentrations indicative of reheating of porous AOAs and significant post-agglomeration annealing, but not slower condensation
  • likely formed in the same region as CAIs but experienced cooler condensation temperatures (Fagan et al., 2004)
  • alternatively, but not strongly supported, formation occurred from rapidly cooled igneous melts (Wasson et al., 2004)
  • composed primarily of forsteritic olivine and a refractory component composed of the high-Ca pyroxene Al-Ti-diopside, along with anorthite, spinel, CAIs, and rare melilite; secondary nepheline, sodalite, and other phases may be present as a result of aqueous alteration processes on the parent body (Fagan et al., 2003)
  • FeNi-metal is rare, indicating rapid extraction from the condensation site following forsterite condensation
  • AOA olivine was a precursor to chondrule olivine; AOAs may provide a genetic link between CAIs and low-FeO type-I chondrules via metasomatic processing (Krot et al., 2004) in which low-Ca pyroxene shells have accreted and melting has occurred within less 16O-rich, chondrule-forming nebular regions (Krot et al., 2005; Ruzicka et al., 2011)
  • may be associated with formation of ordinary, rumuruti, and enstatite chondrite groups through removal of varying amounts of AOA fractionate from an initial CI-like composition
  • AOA abundances in the local, isotopically anomalous dust that was precursor to CC chondrules may be responsible for much of the ε50Ti, ε54Cr, and δ16O (i.e., low Δ17O) variability among those chondrules (Schneider et al., 2020)

Schematic Representation of AOA Formation
standby for aoa formation diagram
click on photo for a magnified view

Schematic diagram credit: Marrocchi et al. PNAS, vol. 116, #47, (2019, open access link)
'Rapid condensation of the first Solar System solids'

Excellent images of AOAs can be seen in John Kashuba's article 'Amoeboid Olivine Aggregates'
published in the November 2015 issue of Meteorite Times Magazine.

FUN CAIs (Fractionated and Unknown Nuclear isotope anomalies)

  • rare type of inclusion present in some carbonaceous chondrite groups
  • large isotopic anomalies are present for O, Mg, and Si, while nonlinear isotopic anomalies exist for Ca, Sr, Ba, Nd, Sm, Ti, and Cr
  • anomalies resulted from the mixing of components from normal nucleosynthetic processes (e.g., the rapid neutron capture [r-] process in Type Ia SN, type II SN) in unusual proportions
  • subsequently subjected to mass fractionation processes (e.g., Rayleigh distillation), possibly within gaseous protoplanets
  • volatility-fractionated REE patterns
  • abundant spinel and large isotopic fractionations may indicate a higher temperature origin
  • magnesium in the inclusions is isotopically heavy
  • lack the 26Mg excess that is present in other CAIs, suggesting they formed very early, prior to 26Al incorporation into solar nebula
  • they were segregated quickly from the region of solar flare irradiation to preserve evidence of the composition of the pristine protosolar molecular cloud
  • the group includes some mass fractionated hibonite inclusions with or without nucleosynthetic anomalies

µCAIs (Bland et al., 2007)

  • a distinct population of µm-sized CAI inclusions; not fragments of larger CAIs
  • consist of corundum cores with complete Al, Ca-containing rims
  • O-isotopic compositions are unique
CAIs are also classified based on REE abundances into Groups I–VI. For example, Group I formed from an essentially unfractionated nebular gas, and Group II formed by condensation of a fractionated nebular gas depleted in an ultra-refractory component (e.g., fine-grained CAIs).

PLACs (platy hibonite crystals)

  • rare type of inclusion (60–110 µm) present in carbonaceous chondrites, particularly the CM group
  • gas–solid nebular condensate which lacks the 26Mg excess present in CAIs; i.e., may pre-date injection of 26Al into the disk
  • represent some of the first solids (corundum, hibonite) that formed in the solar nebula following the low-velocity impact of a stellar shock front with the protosolar cloud, triggering its collapse
  • formed prior to the incorporation and/or homogenization of freshly synthesized short-lived nuclides like 26Al
  • formed rapidly over a span of 10,000–100,000 years
  • formed prior to CV CAIs acquiring the "canonical" 26Al/27Al initial ratio (5.2 [±0.2] × 10–5); nuclides would not be manifest in CAIs until a few 100,000 years later
  • large nucleosynthetic anomalies are present for Ca, Ti, and Si, which were implanted by interstellar dust grains
  • volatility-fractionated REE patterns
  • the short-lived nuclide 41Ca is absent
  • formed in a highly 16O-enriched reservoir, probably close to the protoSun
  • plots more broadly spread about the CCAM (carbonaceous chondrite anhydrous mineral) line relative to SHIBs on an oxygen three-isotope diagram (see below)
  • may derive from larger PLAC-like CAIs like the ~175 µm A-COR-01 refractory inclusion from ALHA77307 (CO3.0)

standby for shib oxygen-three diagram
Diagram credit: Kööp et al., GCA, vol. 184, pg. 164 (2016)
'New constraints on the relationship between 26Al and oxygen, calcium, and titanium isotopic variation
in the early Solar System from a multielement isotopic study of spinel-hibonite inclusions'

SHIBs (spinel–hibonite spherules)

  • rare type of hibonite grain (50–100 µm) present in CM carbonaceous chondrite group
  • show evidence of in situ decay of 26Al
  • early condensates that formed rapidly over a span of 10,000–100,000 years
  • most likely formed by late reprocessing ~100,000–700,000 years after CV CAI formation
  • formed at lower temperatures than PLACs, in a region already depleted in the most refractory REEs
  • O-isotopes more similar to CAIs in CR chondrites and Acfer 094 than to PLACs
  • formed in a homogeneous, highly 16O-enriched reservoir
  • define a tight cluster along the CCAM (carbonaceous chondrite anhydrous mineral) and PCM (primitive chondrule mixing) lines on an oxygen three-isotope diagram (see below)

standby for shib oxygen-three diagram
Diagram credit: Kööp et al., GCA, vol. 184, pg. 164 (2016)
'New constraints on the relationship between 26Al and oxygen, calcium, and titanium isotopic variation
in the early Solar System from a multielement isotopic study of spinel-hibonite inclusions'

Selected References (see also references linked within text):

Planetary Materials, Reviews in Mineralogy, J.J. Papike (editor), vol. 36, (1998)

How the Type B1 CAIs Got Their Melilite Mantles, Richter et al., LPSC XXXIII, #1901 (2002)

Oxygen isotopic compositions and origins of calcium–aluminum-rich inclusions and chondrules, E. Scott and A. Krot, MAPS, vol. 36, #10 (2001)

Early solar system events and timescales, G. Lugmair and A. Shukolyukov, MAPS, vol. 36, #8 (2001)

The formation of rims on calcium–aluminum-rich inclusions: Step I–Flash heating, D. Wark and W. Boynton, MAPS, vol. 36, #8 (2001)

Precursors of Type C inclusions—Evidences from the new kind of anorthite–spinel-rich inclusions in the Ningqiang carbonaceous chondrite, Y. Lin and M. Kimura, LPSC XXVIII, #1067 (1997)

A Comprehensive Study of Pristine, Fine-grained, Spinel-rich Inclusions from the Leoville and Efremovka CV3 Chondrites, I: Petrology, MacPherson et al., LPSC XXXIII, #1526 (2002)

Making Calcium–Aluminum-rich Inclusions and Chondrules near the Young Sun by Flares, F. Shu et al., MAPS, vol. 35, suppl. (2000)

On the Remelting of Type B Calcium–Aluminum-rich Inclusions, H. Connolly and D. Burnett, MAPS, vol. 35, suppl. (2000)

TEM study of compact Type A Ca,Al-rich inclusions from CV3 chondrites: Clues to their origin, A. Greshake et al., MAPS, vol. 33, #1 (1998)

In situ formation of palisade bodies in Ca,Al-rich refractory inclusions, S. Simon and L. Grossman, Meteoritics, vol. 32 (1997)

The origin of type C inclusions from carbonaceous chondrites, J. Beckett and L. Grossman, EPSL, vol. 89, #1 (1988)

Mineralogy and petrography of amoeboid olivine aggregates from the reduced CV3 chondrites Efremovka, Leoville and Vigarano: Products of nebular condensation, accretion and annealing, M. Komatsu et al., MAPS, vol. 36, #5 (2001)

Insights into the Formation of Type B2 Refractory Inclusions, S. Simon and L. Grossman, LPSC XXXIV, #1796 (2003)

The identification of meteorite inclusions with isotope anomalies, D. Papanastassiou and C. Brigham, Astrophysical Journal, vol. 338 (1989)

The origin of the 'FUN' anomalies and the high temperature inclusions in the Allende meteorite, G. Consolmagno and A. Cameron, Moon and the Planets, vol. 23 (1980)

Isotopic Heterogeneity and Correlated Isotope Fractionation in Purple FUN Inclusions, C. Brigham et al., LPSC Abstracts, vol 19 (1988)

On the origin of the Ca–Ti–Cr isotopic anomalies in the inclusion EK-1-4-1 of the Allende-meteorite, K. Kratz et al., Memorie della Società Astronomica Italiana, vol. 72, #2 (2001)

Type C CAIs: New Insights Into Early Solar System Processes, A. Krot et al., 67th Annual Meteoritical Society Meeting, #5042 (2004)

Formation of Chondritic refractory inclusions: the astrophysical setting, J. Wood, GCA, vol. 68, #19 (2004)

Evaporation of cmas-liquids under reducing conditions: constraints on the formation of type B1 CAIs, A. Davis et al., NIPR International Symposium (2003)

TEM/SEM Evidence for residual melt inclusions in type B1 CAIs, J. Paque et al., LPSC XXXVIII, #1755 (2007)

Type C Ca,Al-rich inclusions from Allende: Evidence for multistage formation, A. Krot et al., GCA, vol. 71, #18 (2007)

The White Angel: A unique wollastonite-bearing, mass-fractionated refractory inclusion from the Leoville CV3 carbonaceous chondrite, C. Cailet Komorowski et al., MAPS, vol. 42, #7/8 (2007)

Primordial compositions of refractory inclusions, L. Grossman et al., GCA, vol. 72 (2008)

Oxygen isotopic compositions of Allende Type C CAIs: Evidence for isotopic exchange during nebular melting and asteroidal metamorphism, A. Krot et al., GCA, vol. 72 (2008)

Nebular history of amoeboid olivine aggregates, N. Sugiura et al., MAPS, vol. 44, #4 (2009)

Origin and Chronology of Chondritic Components: A Review, A. Krot et al., GCA, vol. 73 (2009)

Refractory Phases in Primitive Meteorites Devoid of 26Al and 41Ca: Representative Samples of First Solar System Solids?, S. Sahijpal and J. Goswami, The Astrophysical Journal Letters, vol. 509, #2, L137 (1998)

Isotopic records in CM hibonites: Implications for timescales of mixing of isotope reservoirs in the solar nebula, Liu et al., GCA, vol. 73 (2009)

A New Model for the Origin of Type-B CAIs, A. Rubin, 42nd LPSC, #1015 (2011)

Amoeboid olivine aggregates (AOAs) in the Efremovka, Leoville, and Vigarano (CV3) chondrites: A record of condensate evolution in the solar nebula, Ruzicka et al., GCA, vol. 79 (2012)

Forsterite-bearing type B refractory inclusions from CV3 chondrites: From aggregates to volatilized melt droplets, Bullock et al., MAPS, vol. 47, #12 (2012)

New constraints on the relationship between 26Al and oxygen, calcium, and titanium isotopic variation in the early Solar System from a multielement isotopic study of spinel-hibonite inclusions, Kööp et al., GCA, vol. 184 (2016)

PSRD article by G. Jeffrey Taylor: "Dating Transient Heating Events in the Solar Protoplanetary Disk", November 16, 2012

Formation of disk- and bowl-shaped igneous Ca,Al-rich inclusions: Constraints from their morphology, textures, mineralogy and modelling, Lorenz et al., Chemie der Erde—Geochemistry, vol. 79, #4 (2019)

Rapid condensation of the first Solar System solids, Marrocchi et al., PNAS, vol. 116, #47, (2019)

Variations in initial 26Al/27Al ratios among fine-grained Ca-Al-rich inclusions from reduced CV chondrites, Kawasaki et al., GCA, vol. 279 (2020)

Early evolution of the solar accretion disk inferred from Cr-Ti-O isotopes in individual chondrules, Schneider et al., EPSL, vol. 551 (1 Dec 2020)

One of the earliest refractory inclusions and its implications for solar system history, Bodénan et al., GCA, vol. 286 (2020)

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