Laurence Garvie

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Introduction: In the 1960s, prior to the widespread use of TEMs, several papers described rounded, micron-sized organic particles from carbonaceous chondrite (CC) meteorites [1-3]. Some of these particles were hollow. Except for two early TEM studies [4, 5], the rounded structures were essentially neglected until similar material was discovered in the(More)
The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in ordinary cubic (c-) diamond (space group: Fd-3m). We show, using(More)
Lonsdaleite, also called hexagonal diamond, has been widely used as a marker of asteroidal impacts. It is thought to play a central role during the graphite-to-diamond transformation, and calculations suggest that it possesses mechanical properties superior to diamond. However, despite extensive efforts, lonsdaleite has never been produced or described as a(More)
Introduction: It has long been recognized that igneous rims (IRs) around chondrules are indicative of a second heating event, occurring after a dustrich mantle was acquired [1-8,14,15]. The textures of IRs suggest they were formed by the same type of heating mechanism as the majority of chondrules [1-8]. IRs have igneous textures, and contain larger,(More)
Oriented single crystals of the high-temperature phase of KNO(3) (phase III), a ferroelectric compound that may also occur as an atmospheric aerosol particle, were grown at room temperature and pressure by atomizing a solution of KNO(3) in water and allowing droplets to dry on a glass substrate. The crystals are up to 1 mm across and are stable unless(More)
Introduction: CM chondrites are primitive rocks that experienced aqueous alteration in the early solar system. Their matrices and fine-grained rims (FGRs) sustained the effects of alteration, and the minerals within them hold clues to the aqueous reactions. Sheet silicates are an important product of alteration, and those of the serpentine group are(More)
Introduction: The first reports of " hard particles " in the Canyon Diablo meteorite dates to 1891 [1], and they were identified as diamond by X-ray diffraction in 1939 [2]. More recent X-ray diffraction studies showed that the Canyon Diablo " diamonds " are composed of various proportions of diamond, lonsdaleite, and graphite [2, 3]. Lonsdaleite is a(More)
Alkali halides such as calcium fluoride all have color center defects that absorb light in the visible region. Using a moncochromator equipped, aberration corrected, scanning transmission electron microscope (STEM) we recorded spectra showing the time evolution of the generation of F and H centers in calcium fluoride. The final stage of electron beam(More)
Introduction: The primitive character and hy-drated mineralogy of the CM chondrites offers insight into some of the earliest reactions between solids and water. Such reactions profoundly affected the matrices and fine-grained rims (FGRs) [1-4], two of the most significant components of these meteorites [5]. We are using EELS combined with a transmission(More)
Cacti contain large quantities of Ca-oxalate biominerals, with C derived from atmospheric CO2. Their death releases these biominerals into the environment, which subsequently transform to calcite via a monohydrocalcite intermediate. Here, the fate of Ca-oxalates released by plants in arid environments is investigated. This novel and widespread form of(More)