BYU-IDAHO METEORITE ANALYSIS

by

Eric S. Bridenstine

A senior thesis submitted to the faculty of

Brigham Young University - Idaho in partial fulfillment of the requirements for the degree of

Bachelor of Science

Department of Physics

Brigham Young University - Idaho

April 2020

Copyright © 2020 Eric S. Bridenstine

All Rights Reserved

BRIGHAM YOUNG UNIVERSITY - IDAHO

DEPARTMENT APPROVAL

of a senior thesis submitted by

Eric S. Bridenstine

This thesis has been reviewed by the research committee, senior thesis coor- dinator, and department chair and has been found to be satisfactory.

Date Stephen McNeil, Advisor

Date David Oliphant, Senior Thesis Coordinator

Date Brian Tonks, Committee Member

Date Stephen McNeil, Committee Member

Date Todd Lines, Chair

ABSTRACT

BYU-IDAHO METEORITE ANALYSIS

Eric S. Bridenstine

Department of Physics

Bachelor of Science

I analyzed meteorites using two methods. One used an X-ray fluorescence spectrometer on the whole meteorite to detect elements. The chemical analysis method used an inductively coupled plasma instrument and involved dissolving a chip of each meteorite.

ACKNOWLEDGMENTS

All equipment and meteorites were provided by BYU-Idaho. Every step of this project benefited from Brother McNeil’s help. Brother Heywood of the chemistry department guided this project to have a chemical analysis method of any efficacy. The assistance of physics student Bryce Pass and guidance of chemistry student Shawn Allen standard proved invaluable in preparing meteorite samples and a magnesium standard for chemical analysis. I also acknowledge my family for their support through the various setbacks of this project.

Contents

Table of Contents xi

List of Figures xiii

1 Introduction1 1.1 Meteorite Background Information...... 1 1.1.1 Formation...... 1 1.1.2 Material...... 3 1.1.3 Petrology and Determining Petrologic Type...... 5 1.2 Classifications...... 6 1.2.1 History...... 6 1.2.2 Finds and Falls...... 8 1.2.3 Clast Identification and Analysis...... 8 1.3 Northwest Africa Meteorite...... 9

2 Procedures 11 2.1 Preparing Samples...... 12 2.2 X-Ray Fluorescence...... 13 2.2.1 Ionization by X-Rays...... 13 2.2.2 XRF Hardware...... 13 2.2.3 XRF Software...... 14 2.3 Chemical Analysis by Inductively Coupled Plasma Instrument.... 16

3 Results 19 3.1 Spectra...... 19 3.2 Elemental Abundance and Classification...... 20 3.3 Errors...... 20

4 Conclusion 23

Bibliography 25

A Lithic Clasts and Chondrules 27

xi xii CONTENTS

B XRF Spectra 29 List of Figures

1.1 Undifferentiated and Differentiated bodies...... 2 1.2 Fusion crust and shock darkening...... 5 1.3 Meteorite family...... 7 1.4 Pallasite...... 9

2.1 Setup for XRF Spectrometer...... 14 2.2 Post-Processing Spectrum...... 15 2.3 Calibration Curves for...... 17

3.1 ICP Analysis Mass results...... 21

A.1 Clasts and Chondrules closeup...... 28

B.1 316SS spectra data...... 30 B.2 BYUI001 spectra data...... 30 B.3 NWA869 spectra data...... 31

xiii

Chapter 1

Introduction

1.1 Meteorite Background Information

1.1.1 Formation

One of the principal goals of meteorite analysis is to gain a better understanding of the formation of the solar system. Early in the solar system’s formation, gravitational accretion formed a protosun surrounded by a spinning flattened nebula of heated gas and dust collectively referred to as a protoplanetary disk [1]. Gravity caused the hot gas and dust to accrete into countless solid bodies. This solid matter makes up the solid bodies in the current solar system but most of them have undergone changes that erased evidence of their early conditions.

When a forming body becomes hot enough the constituent material melts and mixes in a destructive process known as differentiation. A body’s own gravity sorts its mixed interiors by density, stratifying its composition. Differentiated bodies have a solid metal core, a mantle with a mixture of metals and rocky material, and a crust depleted in metals. Particularly large bodies such as the terrestrial planets and some moons have enough mass that gravitational compression provided enough heat for 1 2 Chapter 1 Introduction

Figure 1.1 Almost all meteorites can be broadly classified by region of origin. Note that Pallasites are the most common form of achondritic stony- iron meteorite. differentiation.

Asteroids are smaller bodies and they have not all undergone full differentiation.

Material that originates from these asteroids and survives passing through Earth’s atmosphere are the primary source of evidence for their composition. Figure 1.1 shows this relationship between a meteorite and its parent body. Asteroids have radii smaller than 500 km and have ≤ 0.03g, a radius of 100 km would only increase internal temperatures by a maximum of 6 K so other heat sources must be the cause of any differentiation in asteroids [2].

Round mineral inclusions referred to as chondrules appear in many asteroids and chondrite refers to a meteorite with chondrules present. Models of solar system for- mation must account for the evidence within chondrules to determine the timing of their formation compared with the planets and other bodies. The round shape of 1.1 Meteorite Background Information 3 a chondrule implies that they were once fully or partially melted droplets of rock, though the conditions of low pressure in the protoplanetary disk should have pre- vented the nebular gas from simply condensing into them [1]. Other likely times for chondrule formation are during or shortly after gravitational accretion form a solid body.

Without gravitational compression, different heat sources must be responsible for differentiation in asteroids and must provide a temperature of at least 1773 K in some cases [2]. Collisions between two bodies can produce enormous pressure and heat. However impacts with enough force to sufficiently heat the entire interior of either body would shatter them [2]. Radioactive decay is one likely candidate, but radionuclides with long enough half-lives may be ruled out by their lack of presence.

Of the shorter lived radionuclides 26Al is a favored heating candidate because of the presence of its decay product 26Mg. However it is argued that it could only have originated from a nearby supernova and an even distribution of 26Al could have caused every asteroid to undergo differentiation [2]. A heating source that accounts for varied levels of differentiation is electrical conduction heating caused by solar wind from the developing protosun. The heating effect would have varied based upon distance from the star and would have only been temporary.

1.1.2 Material

Examination of the material within a meteorite informs us about the history of their parent bodies. The heat of differentiation removes material like water, carbon, amino acids, gasses, and other volatile compounds succinctly referred to as volatiles.

Though they are not usually referred to as volatiles, only a few known chondrules have completely escaped transformation by metamorphic and aqueous processes. Chon- dritic asteroids as well as comets were formed from the primitive material of the solar 4 Chapter 1 Introduction systems formation such as Ca rich inclusions (CAIs) as well as pre-solar dust [3].

Chondrites near-universally contain chondrules, up to 80% chondrules by volume, though the chondrules may have undergone severe alteration. Chondrules themselves consist of the rock forming minerals olivine and pyroxene. Olivine comes in two forms; fayalite (Fe2SiO4) and forsterite (Mg2SiO4), while pyroxene can consist of a variety of metal ions compounded with Al2O6 or Si2O6. Much of the remainder of a chondrites mass consists of a stony matrix formed from fine dust, and pre-solar grains are embedded in this matrix [4].

Most irons consist of a single metal mass, usually an Fe-Ni alloy of between 5-62

% nickel with trace amounts of other metals, though the iron meteorite classification allows for up to 30% mineral inclusions. Stony-irons contain between 30-70% Fe-Ni alloy as well as various silicates and minerals. Pallasites are stony-irons thought to originate from the core-mantle boundary of a differentiated body; olivine is the most prevalent mineral and the metal appears in a lattice matrix form. Mesosiderites are stony-irons with the metal in fragmented forms mixed with igneous rock fragments and likely form from collisions between two asteroids. Achondrites are igneous, silicate rich stones containing a variety of minerals and 0-4% Fe-Ni granules [5].

Over 86% of meteorites consist of chondrites and with the abundance of samples they require more specific classification. They are usually classified based on their free metal content: Enstatite (E) ∼ a rare category with 35% free Fe-Ni granules and mineral enstatite (MgSiO3); High iron (H) ∼ with ∼19% Fe-Ni; Low iron (L) ∼ average 9% Fe-Ni; Low iron, Low metal (LL) and High iron, Low metal (HL) with

∼5% Fe-Ni granules as well as 15-30% iron oxide [6], both present in mineral or free metal forms respectively.

Some chondritic asteroids accrete ice after their formation and the subsequent aqueous alterations can transform their chondrules into clay. Of these the car- 1.1 Meteorite Background Information 5

Figure 1.2 This meteorite specimen exhibits abundant black shock veins and visible metal. Most of the outside surface bears black fusion crust. [7] bonaceous chondrites, named for containing carbon, possess the highest amount of volatiles [3]. They are the oldest objects in the solar system and excepting volatiles are the objects which most closely match the elemental composition of the sun.

1.1.3 Petrology and Determining Petrologic Type

Petrology, also referred to as petrography, refers to information that may be ob- tained by visual examination of a specimen. Some details such as fine shock darkening only appear when light strikes the surface from a certain direction, and this is best achieved with proper usage of polarized light [6]. Petrology with polarizing microscopy is common in geology as anisotropic material is present in many rocks.

The friction of passing through Earth’s atmosphere heats and wears away the surfaces of meteorites, leaving fusion crust on the surface. The presence of fusion crust is one of the few features that may be determined without the assistance of any instruments as shown in figure 1.2. It is the internal chemical composition changes 6 Chapter 1 Introduction that are of most interest because they occur on the parent asteroid of a meteorite and reveal information about these asteroids. The surfaces of meteorite finds are worn away by wind and other forms of erosion, but ’weathering’ refers to the oxidation of Fe or of silicates containing Fe. Weathering is recorded on a scale ranging from pristine W0 (Fe is present with no apparent oxidation) to W7 (complete oxidation of metals as well as massive replacement of silicates by clay minerals and oxides) [8].

The petrologic type refers to the alteration of chondrules by aqueous or metamor- phic processes and is typically appended to the meteorites letter designation for metal content. The petrologic scale has pristine chondrules at 3, chondrules obliterated by aqueous processes at 1, and chondrules transformed entirely by metamorphic pro- cesses at 7. The percent content of fayalite compared to forsterite in the meteorites olivine can aid in classification and is recorded. There is also a shock scale which ranges from S1 (< 5 gPa with no visible impact shock) to S6 (75-90 gPa with glass formation and recrystallization) [8] as greater shocks melt the rock. Space based colli- sions between two bodies cause far greater shock to the meteorite than its atmospheric entry and Earth collision, and all asteroids have been affected by shock to differing degrees. An example classification [8] of a low metal chondrite, or L chondrite, with all these indicators present from Lucerne Valley: LV001 +34°N +116°W, L6, Fa 24.2 (S2) (W3)

1.2 Classifications

1.2.1 History

Terminology has evolved over time but a commonly used hierarchy of terms from less to more specific is order, class, clan, group, and subgroup [6]. The orders are undifferentiated chondrites, partially differentiated primitive achondrites which bear 1.2 Classifications 7

Figure 1.3 ”Alternative classification scheme in which meteorites are linked by origins from common parent bodies or derivation from common nebu- lar reservoirs. Some links are based on petrology, chemistry and O-isotopic compositions (e.g., enstatite chondrites and aubrites), while in other case, the link is based almost completely on O-isotopes (e.g., IVA irons and LL chondrites).” [6] similarities to chondrites in composition, and differentiated achondrites. More specific terms have different meanings depending on meteorite classification scheme used, as there are interpretation disagreements.

”The current classification scheme for meteorites had its beginnings in the 1860s with G. Rose’s classification of the meteorite collection at the University Museum of Berlin and Maskelyne’s classification of the British Museum collection. Rose was the first to split stones into chondrites and nonchondrites. Maskelyne classified mete- orites into siderites (irons), siderolites (stony-irons), and aerolites (stones).” [6] The referenced current classification scheme is based on body of origin and is shown in

figure 1.3.

With regards to the stony, stony-iron, or iron descriptions, these are all applicable to some classes of achondrites. However chondrites consist almost exclusively of stony meteorites. There is a good consensus around these subgroups of meteorites but disagreement for objects that are not obviously from the same parent body. There 8 Chapter 1 Introduction are also unique meteorite specimens that may represent the first samples of new subcategories [6].

1.2.2 Finds and Falls

Meteorites are referred to as finds if they cannot be associated with any fall event.

A fall can be traced to a particular event and thus to an origin body. The elemental contamination effects of earth-based exposure whether over determinate or indeter- minate time must be considered.

Most of the mass of a meteorite is lost during atmospheric reentry as the surface melts, smoothing angled edges and disintegrating loose fragments. The presence of darkened fusion crust on the surface from re-entry is one indicator of a meteorite, though fusion crusts may have weathered away in many finds. Various impact melt rocks or glasses are also formed by the force of the impact. [8].

Many meteorite finds are discovered in deserts as the lack of moisture better preserves them, most commonly in Antarctica or northern Africa. Finds or falls are given an acronym for the region they were recovered from. A plurality of meteorites in any one region such as the aforementioned deserts leads to appending a number, as in the case of NWA869 from Northwest Africa.

1.2.3 Clast Identification and Analysis

A lithic clast is a worn down fragment or grain that is part of another rock.

As the parent bodies of meteorites are formed from accretion they contain multiple clasts, only some of which are chondrules. Unlike chondrules, clasts may be present in differentiated bodies. This is made readily apparent by the cross section of a stony-iron pallasite in figure 1.4. 1.3 Northwest Africa Meteorite 9

Figure 1.4 Imiliac Pallasite cross section demonstrating large olivine clasts in a nickel-iron matrix. [9]

Clasts in meteorites vary in size between cm to sub mm scales. Polarized light microscopy or a scanning electron microscope may be necessary to visually resolve all the clasts. Without the equipment necessary to resolve and distinguish the clasts the analyses performed consisted of bulk material analysis of meteorites.

NWA869’s analysis distinguishes between different clasts and the rest of the me- teorite’s material. Listed clasts include type < 3.5 chondrite clasts, type 4 chondrite clasts, type 5 and 6 chondrite clasts, shock darkened chondrite clasts, unequilibriated microbreccia (type 3 particles), impact melt rock clats, and SiO2 bearing objects (quartz). Non-clast entries include bulk material and the clastic matrix. [8]

1.3 Northwest Africa Meteorite

The northwest Africa (NWA) 869 meteorite find is one of the largest in the Sahara.

It has been classified as an L4-6 fragmental breccia and consists of thousands of stones ranging from < 1 g to > 20 kg. It is also notable for containing large amounts of 10 Chapter 1 Introduction noble gasses and being one of the L-chondrites to escape a significant impact event

470 million years ago that disturbed the Ar-Ar age of many meteorites. [8]

The procedures and equipment that have already been used on NWA869 are ex- tensive and include petrography with a polarizing microscope, mineral analysis with a scanning electron microscope equipped with an energy dispersive X-ray (EDX) anal- ysis system, chemical analysis by X-Ray Fluorescence (XRF) spectrometer, oxygen isotope analysis with infrared laser fluorination system, and 40Ar-39Ar dating with a reactor at the Geesthacht Neutron Facility in Germany [8]. These have been per- formed on seven bulk samples of NWA 869 and 27 of its lithologies, though not every procedure for every sample. One of the objectives was to contribute to covering the entire lithographic inventory of NWA 869 to aid in proper selection of materials in future research [8].

This thesis covers XRF analysis and Inductively Coupled Plasma (ICP) analysis performed on 15 meteorite samples, including a sample of NWA869. As clasts were not properly distinguished, the appropriate entry would be bulk material. The analyses covered a smaller range of elements, only metals. Chapter 2

Procedures

The analyzed meteorites were NWA 869, Gold Basin, and 15 unclassified mete- orites from various regions in the Sahara desert. Classification of meteorites is largely dependent on the Fe/Ni ratio and in part on the presence or absence of Mg. The majority of the meteorites being unclassified presented a challenge for the research.

NWA 869 meteorite literature [8] provides methods for analyzing meteorites with an XRF spectrometer and ICP instrument. These methods were modified based on limited equipment. Prior results for XRF analysis with BYUI’s XRF spectrometer revealed a difficulty in capturing spectra of low enough wavelength to indicate Mg.

Meteorite literature on the NWA869 [8] and Gold Basin [10] meteorites publishes the expected ratios for Mg, Fe, and Ni. This provides a source to compare our spectra and chemical analysis results to.

After analyzing the available literature it was clear that dissolving Fe in the sam- ples would be the most difficult characteristic of the chemical analysis procedure.

Dissolving the sample in aqua regia and filtering it with carbon mesh is a common procedure in early meteorite analysis [11]. Hydrochloric acid (HCL) was chosen as a less hazardous alternative to aqua regia or hydrofluoric acid and to contribute to the

11 12 Chapter 2 Procedures

lack of meteorite analysis regarding the dissolution of Fe in HCl.

2.1 Preparing Samples

In order to perform the chemical analyses a chip from the meteorite samples was

removed and dissolved. A diamond bladed wet saw was used for the cutting. A cross

section was removed from each meteorite and the crust pared back to account for any

Earth element contamination.

Hydrochloric acid was chosen to dissolve the meteorite chips. The meteorite chips

were separately ground into fine powder using an agate mortar and pestle. Small

pellets believed to be iron silicate inclusions in some of the chips were unable to be

fully ground. The ground powder from each meteorite as well as a Mg standard were

prepared with the same process. This consisted of dissolving in 10 mL of HCl, allowing

several minutes to settle, diluting in 100 mL of water, then 10 mL of the resulting

solution diluted to 250 mL. This procedure measures bulk elemental composition

as without a scanning electron microscope determining which clast or clasts were

sampled is untenable.

Fe and Ni standards with 10000 ±1 ppm and 9992 ±1 ppm respectively were distilled to 10 mL with ∼20 ppm for preparing a stock solution. The Mg standard was calculated as having 210 ±1 ppm and distilled to 10 mL with an intended 10 ppm, but due to an oversight a different Mg standard was used with 1010 ±10 ppm resulting in ∼50 ppm. The stock solution was prepared in 5 concentrations, the base,

1/2, 1/4, 1/10, and 1/100. These stock solutions and the meteorite samples were

stored in volumetric flasks sealed with paraffin wax until the ICP instrument was

available. 2.2 X-Ray Fluorescence 13

2.2 X-Ray Fluorescence

2.2.1 Ionization by X-Rays

An atom’s inherent energy is associated with the energy level of its electrons. An

atom can gain energy by colliding with another particle, though this energy is rarely

kept for long as particles trend towards low energy states. When an electron in an

atom transitions from a high energy state to a lower energy state a photon is emitted

with the difference in energy.

Due to quantum mechanics each individual electron can only have particular,

discrete energy levels and not any energy values between these energy levels. Because

of this each element has characteristic photon emission lines at certain energies such

as the Kα or Kβ emission lines in Fe. The elements in an energized object may all be identified based on their collective emission spectrum.

An energized object emits X-ray photons at a predictable reflection angle based on the original incidence angle. A properly placed X-ray detector captures the resulting

X-rays rather than needing to surround the energized object. The material of an

X-ray detector is ionized by the incoming photons and the charge produced is quickly recorded.

2.2.2 XRF Hardware

The XRF spectrometer consisted of an X-ray tube, power supply, Mini-X X-ray detector and sample fixture contained within aluminum radiation shielding. An X- ray tube is a vacuum tube consisting of an electron emitting cathode and electron absorbing anode. This X-Ray tube is positioned to emit X-rays toward the sample

fixture. The detector was set at a 45° angle from the X-ray tube to best amplify the signal from reflected X-rays. This layout is shown in figure 2.1. 14 Chapter 2 Procedures

Figure 2.1 Basic layout for XRF spectrometer. XRS is detector, XRG is X-Ray tube. [12]

The radiation shielding acts as a Faraday cage and so holes for cables in the back of the shielding do not compromise its safety. A Geiger counter had been used to test radiation levels during device operation and they were low enough to be comparable to the amount that escapes a microwave oven; well within safety levels. As a safety feature the X-Ray tube cannot be powered until the radiation shielding is closed and latched.

Unfortunately while taking a spectra of the 316SS standard at a high energy level the X-ray tube in the Mini-X became damaged and the XRF spectrometer could no longer maintain voltage properly. The X-Ray tube had been installed for 9 years with infrequent use. The expected life span is 4-6 years or 10,000 - 30,000 hours of use.

2.2.3 XRF Software

Spectra of a stainless steel standard SS316 were taken across a wide range of settings for optimization and in an attempt to detect Mg. Electrical current var- ied from 50-200 µA , voltage from 10-40 kV, and the gain setting from 1.1 - 150 eV/channel. Batches scheduled for a longer duration have a higher resolution to an effective maximum around 3600s. Though the software will stop taking data after the 2.2 X-Ray Fluorescence 15

Figure 2.2 ”The black trace is the original raw spectrum. The blue trace shows the processed spectrum, after correcting for escape peaks, sum peaks, background removal, etc. The red peaks are the result of the deconvolution showing the fitted Gaussian photopeaks. The intensities of the characteristic lines are the net area of the peaks.” [13] allotted time, the X-Ray tube must be manually deactivated to prevent wear from unintentional prolonged usage.

A laptop connected to the XRF hardware manages the settings and the Amptek

DPPMCA data acquisition software receives the output as a raw spectrum. Post- processing techniques are then applied to make corrections such as removing the background, accounting for escape peaks in the material of the detector, and detecting aluminum in the radiation shielding. The user manually assigns the proper emission lines to the spectrum peaks before deconvolution reduces the spectra to only the emission lines. Figure 2.2 shows the spectra at the three steps of this process.

X-ray fluorescence fundamental parameters or XRF-FP is software designed to extract elemental concentration information from spectra. This software is included as part of the Amptek XRF spectrometer and has an unusual dependence on detecting the hardware, even though it is only used after post processing with the DPPMCA 16 Chapter 2 Procedures program. Unfortunately all attempts to use XRF-FP for produced spectra failed due to various software issues.

2.3 Chemical Analysis by Inductively Coupled Plasma

Instrument

An Inductively Coupled Plasma (ICP) instrument has a tube and peristaltic pump to intake solution directly from a volumetric flask. This solution is sprayed as a mist onto an argon-plasma torch between 6000-8000 K. Some of the resulting ions are directed by an interface towards a mass-spectrometer. ICP chemical analysis is capable of detecting a far greater range of elements than an XRF spectrometer.

By providing distilled water and stock solution at 5 concentrations a calibration curve is created with software on a connected computer. This calibration curve shown in figure 2.3 is an educated guess to inform the ICP instrument of the expected range of elemental content. The R2 values for Fe, Ni, and Mg exceeded 0.99990 indicating high precision in the distillation required for preparing stock solutions.

On account of an oversight the Mg standard was prepared with about five times the expected MG. The results indicated Mg abundance values below zero and were thus discarded. When comparing the elemental abundances of Ni and Fe in the

NWA869 meteorite to the minimum and maximum values across its reported clast abundances, Fe exceeded expected values slightly and Ni was well within expected values. 2.3 Chemical Analysis by Inductively Coupled Plasma Instrument 17

Figure 2.3 The calibration curve for our standards. 18 Chapter 2 Procedures Chapter 3

Results

3.1 Spectra

The XRF spectrometer work was completed before the ICP chemical analysis procedures. The NWA869 meteorite article had not been reviewed yet and so XRF spectrometer work began with stainless steel standard SS316, unclassified meteorite

BYUI001, and NWA869. Unfortunately these were the only spectra taken before the failure of the Mini-X X-Ray tube.

The many spectra of SS316 showed the XRF spectrometer could not detect Mg.

Al was present in all spectra in unexpectedly high amounts and it is believed that it was detecting the aluminum radiation shielding. The most useful results were the quantities of Fe and Ni in NWA869 and BYUI001.

Cr and Mo are present in the SS316 standard but were not detected in the analyzed meteorites. The relative abundance of Fe and Ni could be compared but without the

XRF-FP software in working order there is little else that can be gleaned. If the

XRF-FP software had been working then elemental composition data for Fe and Ni could be directly identified rather than extrapolated.

19 20 Chapter 3 Results

3.2 Elemental Abundance and Classification

The results from ICP chemical analysis are much more helpful than the XRF spectra, though with the XRF-FP software that would not be the case. The Fe and

Ni content of all the meteorites is within expected ranges for chondritic meteorites.

Two exceptions are BYUI001 and BYUI015 which have almost absent Fe.

Extensive petrological work was not performed on the meteorites. In the process of extracting samples the presence of chondrites was confirmed visually in all meteorite samples. The meteorites also lacked the characteristics of impact melt rock but this does not offer guidance on what other clasts are present.

NWA869 meteorite literature [8] lists elemental composition in the form of miner- als such as FeO, MgO, or SiO2. Evacuation of the oxygen atoms is a step recommended in some meteorite literature. Expanding the procedure to detect for more elements in the meteorites is a logical improvement.

3.3 Errors

The most restrictive limitation on the work was the lack of a scanning electron microscope. Without one it wasn’t feasible to sort the meteorite samples into indi- vidual clasts. Scanning electron microscopes used on a cross section of a meteorite are sufficient to classify them as well.

The mass% results of the ICP-JAAS analysis are shown in figure 3.1 and table 3.1.

BYUI015’s low Fe content could be explained by a failure to grind Fe into the powder chosen for dissolution. HCl may not have fully dissolved the Fe and the concentrations could be brought down. Solid material was filtered out as part of preparing each liquid sample and this could have impacted the elemental concentrations. 3.3 Errors 21

Figure 3.1 Magnesium results have been discarded as they indicated nega- tive abundances. Due to oversights, samples of BYUI003 and BYUI005 were not prepared and no data was collected for them.

Table 3.1 Meteorite composition results.

Begin of Table

Mass % Ni Mass% Fe

BYUI001 0.08757 1.53814

BYUI002 0.54796 15.37584

BYUI004 0.44798 13.84492

BYUI006 0.63024 20.02551

BYUI007 1.07827 22.97842

BYUI008 0.41291 17.61121

BYUI009 0.48649 17.40460

BYUI010 0.48000 18.26688 22 Chapter 3 Results

Continuation of Table 3.1

Mass % Ni Mass% Fe

BYUI011 0.51484 20.52583

BYUI012A 0.61212 17.98376

BYUI012B 0.75656 20.20103

BYUI013 0.50487 17.51609

BYUI014 0.76230 21.85744

BYUI015 1.12794 1.17841

NWA869 1.12541 17.06148

Gold Basin 1.29925 17.78200

End of Table

The accuracy of the results is difficult to determine without comparison results available for the BYUI meteorites performed. Examination of the oxygen isotopes within the meteorite samples would have helped narrow down which chondritic class the meteorite samples belonged to. Examination of the noble gases and radionuclides would have given information on the radiation present while the meteoroid was in transit to earth. Chapter 4

Conclusion

Equipment availability can limit experiments in unpredictable ways. The proce- dures of some analytical methods prohibit others, so proper awareness of their use and limitations is important. Clearly defining the goals of an experiment should involve identifying multiple valuable outcomes rather than merely choosing one to search for.

The XRF-Spectrometer at BYU-I does not appear to possess the capabilities to detect Mg. Without functioning XRF-FP software, the XRF-Spectrometer data can only obtain relative values for the mass of elements present rather than mass %. The

ICP analysis procedure appears to give valid data with the exception of Mg, but it is difficult to analyze how using HCl rather than aqua regia affects results.

The results of this thesis are likely of most value to those attempting meteorite analysis with limited equipment. For further analysis of BYU-I’s meteorites with the available equipment, XRF analysis of all the samples is a good first goal. A second research goal would be to get the XRF-FP software working properly for more complete results.

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meteorites using an elemental analyzer and a portable xrs.” https://www.hou.

usra.edu/meetings/lpsc2014/pdf/2700.pdf, 2014. Accessed on 2019-09-28.

[13] A. Inc., Amptek Application Note XRF-1: XRF Spectra and Spectra Analysis

Software. Amptek Inc. Appendix A

Lithic Clasts and Chondrules

27 28 Chapter A Lithic Clasts and Chondrules

Figure A.1 This is used to demonstrate the varying sizes of chondrules, clasts, and matrix in differing meteorites. [6] Appendix B

XRF Spectra

29 30 Chapter B XRF Spectra

Figure B.1 This is a processed spectra of a stainless steel standard 316SS. X-rays with 30kv and 100µA were used. Data was recorded for 3600 seconds across 8192 channels set to 47.059 gain.

Figure B.2 This is a processed spectra of meteorite BYUI001. X-rays with 10kv and 200µA were used. Data was recorded for 2700 seconds across 4096 channels set to 101.827 gain. 31

Figure B.3 This is a processed spectra of meteorite NWA869. X-rays with 20kv and 100µA were used. Data was recorded for 2700 seconds across 8192 channels set to 149.999 gain. 32 Chapter B XRF Spectra