YD IMPACT COMET CRUST

Sectioned igneous slab with metallic-iron inclusions
Suggested YD impact comet-crust meteorite

This article makes the case for a new class of outer solar system meteorites from a siderophile-depleted reservoir older than the well-understood inner solar system asteroid belt reservoir.

Abstract:

    Inner solar system asteroids and chondrites are well characterized and classified, but no meteorite finds on Earth have been specifically attributed to the Kuiper belt, which is suggested here to be because Kuiper belt object (KBO) core rock is the origin of the continental tectonic plates on Earth by way of the late heavy bombardment, and because KBO comet crust is remarkably similar to industrial iron furnace slag. This alternative comet-crust-meteorite supposition requires an alternative solar system model, which predicts the condensation of hot classical KBOs from an old siderophile-depleted ‘trifurcation debris disk’, shortly prior to the subsequent condensation of inner solar system asteroids and chondrites from a binary spiral-in ‘solar-merger debris disk’ at 4,567 Ma.
    Comet Encke and the Taurid meteor stream has been suggested as a possible debris stream of a much larger KBO that fragmented in the inner solar system in the last 20,000 to 30,000 years. The ‘Younger Dryas (YD) impact hypothesis’ suggests that one or more large chunks of the fragmented YD KBO struck the Laurentide ice sheet, circa 12,900 B.P.
    The following is a hypothesis for the formation and composition of the YD KBO, focusing on its suggested rocky-iron crust.
    An alternative solar system formation mechanism designed to explain the 3 sets of twin-binary planets (Jupiter-Saturn, Uranus-Neptune, and Venus-Earth) in our highly-unusual solar system predicts a resulting high-angular-momentum siderophile-depleted (trifurcation) debris disk that lay on the 3-oxygen-isotope terrestrial fractionation line, condensing the old hot-classical KBO population. This twin-binary planet formation mechanism (trifurcation) also requires a former binary-Sun whose binary components spiraled in to merge at 4,567 Ma, creating a luminous red nova (LRN) that likely enveloped the solar system out to the Kuiper belt. And this plasma immersion would have vaporized volatiles from the outer solar system KBOs as well as the inner solar system planets.
    Large KBOs presumably ‘aqueously differentiated’ at formation by streaming instability > 4,567 Ma, melting water ice from the inside out and precipitating authigenic sedimentary cores with a gneissic composition. At 4,567 Ma, immersion in the stellar-merger LRN plasma began boiling the oceans from the outside in, concentrating dissolved solutes into a buoyant floating froth whose surface melted into a densified rocky-iron crust, and plasma exposure chemically reduced a sizable percentage of the iron oxide solute to metallic iron. The YD ‘KBO’ was not necessarily in a Kuiper belt orbit at the time of the stellar-merger LRN, and may instead have had a considerably lower hotter orbit, possibly as a Jupiter-family comet.
    An impact theory origin for the elliptically-shaped Carolina bays was suggested in the early 1930s from aerial photography. The long-axis alignments of the bays fostered a 2007 theory, suggesting they were secondary impacts of large fragments of shattered ice sheet launched into ballistic trajectories from one or more primary bolide impacts on the Laurentide ice sheet, circa 12,900 B.P. About 500,000 Carolina bays are scattered along the Atlantic and Gulf coasts, presumably with a similar density impacting inland, but the cratering damage of inland impacts was comparatively slight and has since been visually erased.
    This hypothesis suggests that ballistic ice-sheet fragments scattered primary bolide material thousands of kilometers from the primary bolide impact on the Laurentide ice sheet, resulting in local super concentrations of comet-crust bolide material in Southeastern Pennsylvania, with lesser concentrations distributed elsewhere. And the relative compressibility of ice sheet ice absorbed the lion’s share of the impact energy, clamping the impact shock wave pressure below the melting point of silicates, preserving comet crust at impact.

Note: The following article may not represent all the latest understanding expressed in the above Abstract.
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High-density rock specimen with cratered surface from City Island, Harrisburg, PA
Suggested YD impact comet-crust meteorite

Introduction:

    No crater has been positively identified for the one or more posited Younger Dryas (YD) impacts on the Laurentide ice sheet in the Great Lakes Region, circa 12,900 BP. And the absence of a primary impact crater reduces the likelihood of identifying primary bolide material, particularly if it belongs to a new class of meteorites that’s a radical departure from inner solar system asteroids and chondrites.

    There is, however, no shortage of spherules, exotic carbon, glass, nanodiamonds, and iridium and platinum enrichments in widely-distributed black mat deposits worldwide, attributed to the Younger Dryas, and in core samples from the Greenland ice sheet dated to the onset of the Younger Dryas. The leading proponents of the YD impact theory suggest that Comet Encke and the Taurid meteor stream are the residue of a much-larger KBO that presumably fragmented in the inner solar system in the last 35,000 years.
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45 kg metallic-iron ‘ring-of-flames’ from Conshohocken, PA
Suggested YD impact comet-crust meteorite

YD impact comet-crust overview:

    The former YD impact bolide KBO from the Kuiper belt is suggested to have possessed an igneous crust that constitutes a new class of siderophile-depleted (low nickel, < 2 ppb iridium) meteorites on Earth, with the largest impact presumably initiating the Younger Dryas, circa 12,900 B.P. Comet Encke and the Taurid meteor stream are likely YD KBO remnants that possess an igneous crust fraction of their bulk composition.
    Igneous comet crust contains frequent millimeter-to-centimeter-scale metallic-iron inclusions in suspension within a basaltic-like matrix that appears to have solidified in a microgravity environment.

    Suggested YD impact comet-crust meteorites are not distributed in a classical strewn field around a primary impact crater or ground zero. Instead, bolide material was fortuitously preserved by impacting the relatively-compressible ice of the Laurentide ice sheet. The relative compressibility of water compared to silicates presumably allowed the target ice sheet ice to clamp the impact shock wave pressure below the melting point of silicates, preserving bolide material from melting on impact.
    Elliptically-shaped Carolina bays along the Atlantic and Gulf coasts of the US, in numbers estimated on the order of 500,000, have been suggested by others to be secondary impact craters of ballistic ice-sheet fragments from a primary impact on the Laurentide ice sheet, circa 12,900 B.P. And presumably a similar density of impacts occurred inland from the coastal Carolina bays, but secondary inland impacts on harder ground caused less damage that has been visually erased by subsequent weathering in the intervening 12,900 years.
    The Laurentide ice sheet provided a fortuitous endothermic target that preserved much of the impacting comet material in pristine condition, including its igneous crust. A primary impact on the ice sheet launched massive fragments of ice sheet, up to a kilometer across, into ballistic trajectories that delivered pristine bollide material as much as a thousand kilometers from the primary impact location.

    The comet crust in Southeastern Pennsylvania is suggested to have been delivered by secondary impacts of ice sheet fragments traveling at several kilometers per second. Some of the ice sheet fragments apparently contained primary bolide material, only a small percentage of which constituted igneous comet crust. The vast volume and distribution of ice sheet fragments necessary to create an estimated 500,000 Carolina bays along the Atlantic seaboard and Gulf coast, presumably a similar inland concentration, compared to the rather constrained distribution of suggested comet crust in Southeastern Pennsylvania indicates that comet crust may be a small percentage of the bulk bolide material, where bulk bolide material is presumably well camaflauged by its similarity to Earth rocks and/or sediments.

    The impulse of secondary ballistic impacts of ice-sheet fragments on thin soil is suggested to have fractured target bedrock, occasionally resulting in discrete boulder fields when impact-brecciated bedrock flowed downhill in debris flows on sloped terrain. (See section, YD IMPACT BOULDER FIELDS). Other areas littered with sharp-edged nominally-weathered boulders not jumbled into boulder fields could also be secondary impact sites, where only a tiny percentage of secondary impact brecciation is expected to have undergone dynamic debris flows to form concentrated boulder fields, many boulders deep.

YD comet-crust exhibits a number of unusual features that occur with variable frequency:
– Gray igneous matrix; constituting variable-sized chunks of gray igneous matrix, with the matrix containing variable-sized metallic-iron inclusions. Some matrix material is highly-vesicular, like scoria, while some matrix material lacks vesicles altogether.
– Magnetite; low and high-grade magnetite with highly-variable physical manifestations.
– Metallic iron; constituting variable-sized chunks of metallic iron from millimeter-scale inclusions up to 100 kg masses, some composed of solid iron and some composed of iron nodules apparently sintered together.
– Some matrix material exhibits an undulating surface, with a ~10-15 cm undulation radius
– Some matrix material exhibits apparent fusion crust, and some fusion crust exhibits apparent flow lines
– All types of YD comet crust exhibit a strong propensity to be variably coated with a white, gritty cement-like coating.
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Alternative solar system model:

Symmetrical flip-flop fragmentation:
    An alternative star formation mechanism, designated ‘symmetrical flip-flop fragmentation’, is suggested to have ‘condensed’ a twin-binary pair of disk instability objects around a large brown-dwarf-mass prestellar/protostellar core, where the twin-binary disk instability (di) objects were much-more massive than the diminutive core. Orbital interplay progressively transferred kinetic energy and angular momentum from the massive twin-binary di object to the diminutive brown dwarf by the mechanism of equipartition, which evaporated the former core into a circumbinary orbit around the twin-binary di objects, as the di objects spiraled inward to conserve system kinetic/potential energy and angular momentum. And di objects evolved into our former binary-Sun.

Trifurcation and its primary debris disk:
    It’s well known that equipartition transfers orbital kinetic energy and angular momentum from more massive objects to less massive objects in close orbital encounters, which is the mass segregation mechanism that evaporates the least massive stars out of globular clusters, causing the most massive stars to sink inward to form a core. Equipartition is also suggested to transfer rotational energy and angular momentum from large to small objects in close orbital encounters, increasing their rotation rate, causing less-massive objects to ‘spin up’. Equipartition is suggested to have caused our former brown dwarf to spin up until it distorted into a bar-mode instability. Additional pumping of rotational energy caused the bar-mode instability to fragment into 3 components by ‘trifurcation’, where the twin bar-mode arms of the brown dwarf gravitationally pinched off into their own Roche spheres to form a twin-binary pair of super-Jupiters-mass objects in orbit around the diminutive residual core. First-generation trifurcation promotes second-generation trifurcation and etc., ultimately creating 4 trifurcation generations of twin-binary objects in our solar system;
– 1st gen. ― binary-Companion (with super-Jupiter-mass components)
– 2nd gen. ― Jupiter-Saturn
– 3rd gen. ― Uranus-Neptune
– 4th gen. ― Venus-Earth
    Trifurcation is presumably an inefficient process, causing a sizable percentage of the trifurcating core to evaporate or boil off. Presuming the trifurcating core was internally differentiated into an iron-nickel (siderophile) inner core, the evaporated material would have been siderophile depleted. Thus, four generations of trifurcation created a siderophile-depleted ‘trifurcation debris disk’ from the homogenous brown dwarf reservoir.
    And the trifurcation debris disk condensed siderophile-depleted Kuiper belt objects (KBOs), presumably by streaming instability, against Neptune’s outer 2:3 mean motion resonance.

Binary-Sun spiral-in merger luminous red nova (LRN), 4,567 Ma:
    Secular perturbation between former binary-Sun and former binary-Companion caused binary-Sun to spiral in and merge in at 4,567 Ma in a luminous red nova (LRN), which briefly created a plasma fireball that apparently engulfed the classical Kuiper belt, vaporizing volatiles from the surface of KBOs and melting the remaining refractory material into an igneous, siderophile-depletd rocky-iron crust.
    The red giant phase of (stellar-merger) luminous red nova LRN M85OT2006-1 would have reached far into the Kuiper belt, with a fireball estimated at R = 2.0 +.6-.4 x 10^4 R☉, and a peak luminosity of about 5 x 10^6 L☉. (Rau et. al. 2007) “Previously published line indices suggest that M85 has a mean stellar age of 1.6+/-0.3 Gyr. If this mean age is representative of the progenitor of M85 OT 2006-1, then we can further constrain its mass to be less than 2 M☉.” (Ofek et al. 2007) If the size of the less than 2 M☉ LRN M85OT2006-1 fireball was in the range of 74–121 AU (R = 2.0 +.6-.4 x 10^4 R☉), then it’s readily conceivable that our greater than 1 M☉ LRN fireball, at 4,567 Ma, should easily have scorched a preexisting Kuiper belt reservoir centered around 43 AU.
    The LRN quickly retreated, leaving a low-angular-momentum ‘LRN debris disk’ in the inner solar system, which ‘condensed’ rocky-iron asteroids, presumably by streaming instability against the Sun’s greatly expanded magnetic corotation radius, and later condensed chondrites by streaming instability against Jupiter’s strongest inner resonances, but the low angular momentum content of the LRN debris disk precluded forming a debris disk at the distance of the Kuiper belt.

Binary-Companion spiral-in merger, ~ 650 Ma:
    Almost 4 billion years later, the super-Jupiter components of binary-Companion spiraled in to merge at about 650 Ma in an asymmetrical merger explosion that gave the newly-merged Companion escape velocity from the Sun. The resulting ‘Companion-merger debris disk’, condensed a young (650 Ma), cold, classical KBO population against Neptune’s outer 2:3 resonance. And this Companion-merger debris disk also coated the old (> 4,567 Ma) hot, classical KBO population with a veneer of binary-Companion merger dust and ice that was not siderophile depleted. This late veneer is suggested to be the origin of most of the iridium and platinum found in YD black mats across North America and elsewhere, as well as the origin of the whitish cement-like coating on many suggested ‘YD impact comet-crust meteorites’.

See section, STARS, PLANETS, MOONS, MINOR PLANETS AND COMETS
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INAA/mass spec analysis of suggested YD impact comet-crust meteorites

YD comet crust origin and characterization:

    Suggested YD comet crust has a remarkably-high calcium oxide content. The assay of two comet crust samples yield 25.69% and 40.28%, which is in line with blast furnace slag (41.7%) (Chemical composition of iron and steel slag). This unfortunate CaO coincidence reduces the chance of comet crust recognition as a natural substance.
    The high CaO content presumably derives from aqueously-dissolved solute and suspended mineral grains in a KBO saltwater ocean maintained at the boiling point by immersion in stellar-merger LRN plasma. Boiling concentrated solutes to saturation point, with tacky solutes creating a buoyant froth that covered the boiling saltwater ocean, and the plasma melted the surface froth into an igneous crust, like the crust on a fluffy souffle. And presumably iron and calcium oxides were heavily represented in the buoyant froth.
    Stellar plasma is chemically reducing, which reduced a sizable fraction of the iron oxide component of the molten froth to metallic iron. The size and density of suspended centimeter-scale metallic-iron inclusions is suggested here to preclude formation on our high-gravity planet.

Gray igneous matrix with metallic-iron inclusions:
    Comet crust is highly variable regarding specimen size, density, matrix to metallic iron ratio, void prevalence, void size, and surface texture. Specimen size ranges from millimeter- to centimeter-scale gravel up to igneous boulders a meter across. Metallic-iron specimens range in size from millimeter-scale inclusions within gray igneous matrix up to 100 kg masses of metallic iron, with little or no associated matrix material. Internal voids in gray igneous matrix range in size, and abundance from specimens with the appearance of volcanic scoria to specimens with a complete absence of voids.

Massive and nodular metallic iron:
    The shape of the iron inclusions and masses is particularly notable, with many bizarre 3 dimensional shapes having no flat top surface, as would be expected from metallic iron which had cooled from a molten state on our high-gravity planet.
    Metallic iron falls into several categories,
1) metallic iron inclusions completely surrounded by gray igneous matrix,
2) massive metallic iron, often with little or no associated igneous matrix, and
3) nodular metallic iron composed of nodular chucks that appear to be sintered together, with little or no igneous matrix.
    The most inexplicable phenomenon for an industrial slag interpretation on our high-gravity planet is the presence of centimeter-scale metallic-iron blebs suspended within the igneous matrix, where the metallic-iron density is about 2-1/2 times that of the surrounding matrix. By comparison, glassy iron furnace slag from historic Joanna furnace, PA contains zillions of microscopic iron spherules clearly evident in thin flakes, backlit under 40X magnification, with a distinct upper size limit.

Nodular metallic iron
Suggested YD impact comet-crust meteorite

Sectioned igneous slab with metallic-iron inclusions
Suggested YD impact comet-crust meteorite

Broken boulder with magnet attached to metallic-iron inclusion
Suggested YD impact comet-crust meteorite

Nodular metallic-iron mass with whitish cement-like coating
Suggested YD impact comet-crust meteorite

Metallic-iron specimens from Doe Run, PA
Suggested YD impact comet-crust meteorites

Magnified (40x) chip of glassy industrial slag from historic Joanna furnace, PA showing metallic-iron spherules

Whitish, gritty, cement-like coating–reliable indicator of YD comet crust:
    Comet crust meteorites typically exhibit a whitish, gritty, cement-like coating. Calcium carbonate mineral grains apparently constitute a significant percentage of the mineral grains in the cement-like coating, which fizzes when exposed to weak acids like vinegar. The mineral grains are presumably of authigenic origin that crystallized out of the boiling salt water ocean, with high agitation rates of the boiling ocean suspending mineral grains larger than those typically found in beach sand. The calcium carbonate component of the gritty cement-like coating may be the origin of the high calcium oxide component of comet crust meteorites, where carbonates may constitute the majority of the fire assay loss on ignition (LOI).
    Whitish cement-like coating is common on both grey igneous matrix and on comet-crust magnetite, but it’s uncommon on metallic iron nodules and uncommon on massive metallic iron, which could be largely be due to rust exfoliation.
    Whitish, cement-like coating is suggested to be one of the most reliable indicators of YD comet crust; however, its absence is not proof against membership. Iron furnace slag is often mixed with comet crust in the waste stream of historic iron furnaces, and the two contrasting materials can most readily differentiated by the presence or absence of a whitish cement-like coating. After years in streams or rivers, however, comet crust will have lost its cement-like coating, and freshly fractured surfaces may lack coating as well.
    Additionally, whitish cement-like coating contains variable concentrations of shiny black magnetic spherules, visually similar to spherules found at the bottom of the 12,900 year old (YD) black mat in North America and elsewhere, but curiously, the cement-like coating does not also contain transparent glassy spherules, which can be common at the bottom of the YD black mat. The presence of black magnetic spherules and absence of translucent, magnetic glassy spherules suggests that the black spherules may be extraterrestrial, whereas translucent glassy spherules may be tektites, formed at Earth impact.
    Finally, ‘steam cleaning’ at impact may be responsible for bleaching cement-like coating white.

Note the typical cement-like coating characteristic of suggested YD impact comet-crust meteorites

Spherules embedded in cellular matrix gleaned from whitish cement-like coating on surface of suggested YD impact comet-crust meteorite

Shiny black spherule gleaned from whitish cement-like coating on the surface of suggested YD impact comet-crust meteorite

Shiny black spherules gleaned from whitish cement-like coating on the surface of suggested YD impact comet-crust meteorite

Shiny black spherules gleaned from whitish cement-like coating on the surface of suggested YD impact comet-crust meteorite

High-density magnetite/hematite:
    Some comet-crust iron is in the metallic state, some mixed in igneous matrix and some appears in the form of iron oxide, with varying degrees of purity. Oddly, comet crust iron oxide has always been found in discrete lumps and never in physical contact with either metallic iron or igneous matrix. No mechanism has been imagined by which iron oxide solute precipitate apparently came to be segregated from other solute precipitate in the buoyant froth.
    Finally, comet crust iron oxide is generally coated with a variable degree of whitish cement-like coating, similar to the coating typical coating igneous matrix material.
    Comet-crust iron oxide has an apparent industrial slag look alike, resembling early-iron-age bloomery slag, and invariably this type of bloomery-like slag has no whitish cement-like coating, telegraphing its terrestrial and presumably industrial origin.

Magnetite with whitish, gritty, cement-like coating

Comet crust with one rounded surface:
    Many comet-crust specimens from Pottstown, PA are roughly triangular in cross section, with one rounded side, resembling a thick slice of pie. The rounded surface was presumably the outer surface of the KBO, directly exposed to LRN plasma. The brief multi-month immersion of KBOs in LRN plasma caused significant volatile loss, accompanied by igneous melting of the surface froth covering the boiling ocean into a rocky-iron crust.
    The radius of the rounded outer surface is typically in the range of 10–15 cm, presumably representing the degree of surface wrinkling due to subsidence of the supporting froth, perhaps caused by progressive collapse of the froth as the LRN plasma subsided.

Large metallic-iron mass with igneous rocky matrix. The undulating top surface is suggested to be part of the wrinkled surface of the former Kuiper belt object.
Suggested YD impact comet-crust meteorite

Pie-slice-shaped specimen, with the rounded side as a fragment of the undulating wrinkled surface of the former Kuiper belt object
Suggested YD impact comet-crust meteorite

Pie-slice-shaped specimen, with the rounded side as a fragment of the undulating wrinkled surface of the former Kuiper belt object
Suggested YD impact comet-crust meteorite

Vesicles absent to strongly vesicular:
    Suggested comet crust is often dismissed by meteorite experts due to the prevalence of vesicles, since vesicles are very uncommon in inner solar system meteorites. Some comet-crust specimens are so saturated with vesicles as to resemble terrestrial volcanic scoria, and presumably formed in a similar fashion, from pressurized outgassing through weak spots in the formerly molten surface of the YD KBO, and some comet crust exhibits no vesicles at all.
    Comet-crust meteorites make frequent appearances in meteorwrong writeups and meteorwrong image galleries, due to their high density, high metallic-iron content, and ferromagnetic attraction to a magnet. The Washington University in St. Louis, Department of Earth and Planetary Sciences, photo gallery of MeteorWrongs appears to include a number of comet-crust specimens, with the following entry numbers; 11, 16, 93, 109, 183, 223, 294, 298, 325.

Large vesicles in specimen from Harrisburg, PA
Suggested YD impact comet-crust meteorite

Fusion crust, some with flow lines:
    Suggested fusion crust on comet-crust specimens varies in coloration from brown to jet black, where the black coloration is likely pristine, and where brown coloration is likely due to subsequent oxidation. Fusion crust is relatively rare, suggesting that most comet crust was physically protected from the ablative atmosphere during its entry through Earth’s atmosphere. Of small hand-sample-sized specimens exhibiting fusion crust, the fusion crust is frequently evident on all sides, whereas on larger (> 10 cm) specimens that fractured upon impact, the impact-fractured surfaces contain no fusion crust. An industrial iron-furnace slag origin can not explain a fusion-crust-like remelted surface on all sides of small hand-sample-sized specimens.
    While fusion crust is easy to spot on rocky comet crust, iron exposed to atmospheric ablation forms regmaglypts rather than fusion crust; however, so far, no regmaglypts have been identified on metallic-iron specimens to date. Ablation may also cause regmaglypts/fusion crust on the surface of comet-crust magnetite, and in magnetite, there does appear to be some evidence of regmaglypts.
    Additionally, a minority of fusion crust specimens appear to exhibit flow lines as well.

Igneous specimens exhibiting apparent fusion crust
Suggested YD impact comet-crust meteorites

Suggested fusion crust on specimens from Phoenixville, PA
Suggested YD impact comet-crust meteorites

Suggested fusion crust on specimen from Phoenixville, PA
Suggested YD impact comet-crust meteorite

Suggested fusion crust with flow lines and embedded spherules in YD impact comet-crust meteorite

Specimen with suggested fusion crust with flow lines
Suggested YD impact comet-crust meteorite

Locations:

Conshohocken, PA:
    A large volume of comet crust has been used to level a triangle of land just off Light Street, Conshohocken, PA (40.0807, -75.3127), readily identifiable on Google satellite due to the herbicide properties of granulated comet crust. The Conshohocken Area also exhibits numerous diabase boulders with sharp edges formed by catastrophic fracturing rather, rather than gradual weathering, suggesting brecciation by a secondary impact by an ice sheet fragment.
    Suggested comet-crust material in Conshohocken is variably mixed with iron furnace slag. In some cases, comet crust material was apparently melted (rather than smelted) for its metallic iron content to create brittle cast iron, since melting required much-lower technology and less energy than smelting iron ore. In the Conshohocken Area, brittle cast iron (suggested to have been derived from melting comet crust) was used to cast window-sash counter weights, with broken chunks of counter weights scattered along the west bank of the Schuylkill River in West Conshohocken.
    Remelted comet-crust slag often contains broken pieces of fire brick and lacks macroscopic metallic-iron inclusions, and tellingly, remelted comet crust slag also lacks the whitish, gritty cement-like coating of pristine comet crust. Remelted comet-crust can be discriminated from smelted iron-furnace slag due to its much-greater density, with the high density of remelted comet crust attributable to its considerable iron-oxide content.

Mound of granular slag-like material from from Conshohocken, PA (40.0807, -75.3127)
Suggested YD impact comet-crust material

Loose metallic-iron nodules from Conshohocken, PA
Suggested YD impact comet-crust material

Phoenixville, PA:
    In Phoenixville, PA, a significant quantity of triangular pie-slice shaped comet-crust fragments
are mixed with a smaller quantity of industrial iron furnace slag from the nearby historic Phoenixville iron works. Here, the industrial slag appears to be of two types, low-density slag smelted in the primary Phoenixville iron works blast furnace, and high-density slag, in small adjunct furnaces melting comet crust for its metallic-iron content. The high incidence of surficial comet crust, with one rounded surface, in the waste stream is presumably because surficial comet crust invariably has a lower metallic-iron content than comet crust from further beneath the surface of the former KBO.
    The slag and comet-crust material has been tumbled into the French Creek ravine along the south bank, between N. Main St. and Ashland St. (40.135, -75.513), just east of the Phoenixville Foundry.

Harrisburg, PA:
    As elsewhere, comet crust has been used as clean fill in the Harrisburg Area. Comet crust in combination with iron-furnace slag has been used to build what appears to be an abandoned road spur off Paxton Ave. between Paxton Ministries and Faulkner Honda (40.2545, -76.8505).
    Comet crust been used as clean fill on the East Shore of the Susquehanna River to extend residential parking on the river side of Front St. in Enola, PA, and the material has been spotted as far west as Wesley Dr. in Mechanicsburg, PA.

Prospecting:
    A strong rare earth magnet is the only necessary prospecting tool for identifying potential comet crust in Southeastern Pennsylvania.

Rare-earth magnet attached to metallic-iron inclusion in specimen
Suggested YD impact comet-crust meteorite

Future work:

– Several comet crust samples were analyzed by INAA for iridium, including one analysis on a metallic-iron inclusion, but no iridium was found down to 5 ppb. INAA does not detect platinum, however, which is a prevalent YD black mat marker, and platinum was found in Greenland ice cores from 12,900 B.P. A recent understanding of hybrid nature comet-crust material suggests that the whitish cement-like coating should be analyzed for iridium and platinum.

– An old age determination (> 4.5 Ga) for comet crust would be the gold standard for a new class of siderophile-depleted meteorites which fails multiple other tests, such as, close association with the historic iron industry, low nickel to iron ratio, absence of iridium, igneous origin, and manifold internal voids.
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References:

Ofek, E. O.; Kulkarni, S. R.; Rau, A.; Cenko, S. B.; Peng, E. W.; Blakeslee, J. P.; Cote, P.; Ferrarese, L;. Jordan, A.; Mei, S.; Puzia, T.; Bradley, L. D.; Magee, D.; Bouwens, R., (2007), The Environment of M85 optical transient 2006-1: constraints on the progenitor age and mass, arXiv:0710.3192 [astro-ph]

Rau, A.; Kulkarni, S. R.; Ofek, E. O.; Yan, L., (2007), Spitzer Observations of the New Luminous Red Nova M85 OT2006-1, The Astrophysical Journal, Volume 659, Issue 2, pp. 1536-1540
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