H. Catherine W. Skinner

Possible vestige of early phosphatic biomineralization in gorgonian octocorals (Coelenterata)

Skeletal carbonate hydroxylapatite, heretofore unknown in modern coelenterates, has been found in the axes and holdfasts of the gorgonian octocoral family Gorgoniidae. This carbonate apatite is a distinctive feature of this family of octocorals and may indicate a previous history of phosphatic skeletal mineralization within this phylum.

A fresh look at sideritic “coprolites”

Abstract Sideritic “coprolites” from the late Miocene of southwest Washington, the Upper Cretaceous of Saskatchewan and Madagascar, and the Permian of China have often been claimed to be pseudofossils. They are here interpreted as intestinal casts (cololites) prefossilized by bacterial activity and later transformed into siderite with no traces of original food particles left. All occurrences are found within fluvial overbank deposits that carry no other vertebrate remains. Their absence could be due to aquifer roll-fronts that destroyed phosphatic bones and teeth but favored siderite precipitation.

A review of apatites, iron and manganese minerals and their roles as indicators of biological activity in black shales

Abstract Biological contribution to the formation of minerals has become more than a descriptive area in geological thought and research. Mechanisms of specific mineral accumulation and deposition in oceancs, lakes, and even desert environment, are studied using interdisciplinary approaches and applied in the interpretation of earth processes. Phosphorus, iron and manganese, are, and probably were, essential elements in life forms. The common minerals of these elements, apatite, and magnetite, for example, can be found in a variety of sedimentary environments, both ancient and modern, where they could be useful indicator minerals to interpret geologic environments. The crystal morphological, structural and chemical (including isotopic) attributes of these usually fine-grained minerals can be compared with bulk chemical and stratigraphic information to augment our understanding of the mechanisms of formation and diagenesis in sediments such as black shales.

Ionic interaction with bone mineral. IV. Varying affinity of synthetic calcium phosphates for Ca2

Abstract The concentration of Ca 2+ and PO 4 3− in the liquid film surrounding the crystals of several synthetic calcium phosphates suspended in an aqueous medium was calculated from 45 Ca 2+ and 32 PO 4 3− exchange studies performed under physiological conditions. This permitted an estimation of the uptake of Ca 2+ and PO 4 3− from solution by the solid phase alone, exclusive of the uptake by the adherent liquid film. The compounds with low calcium-to-phosphate molar ratio (Ca/P) showed a greater affinity for Ca 2+ than those with higher Ca/P. Octacalcium phosphate (Ca/P = 1.33) incorporated considerably more Ca 2+ than PO 4 3− . Tricalcium phosphate (Ca/P = 1.5), Bio-Rad apatite (Ca/P = 1.51), G-D apatite (Ca/P = 1.63), and L-apatite (Ca/P = 1.67), all of which gave apatitic X-ray diffraction patterns, demonstrated an uptake of Ca 2+ in decreasing order, and an uptake of PO 4 3− in increasing order.

Mineralogy of Asbestos Minerals

Over the past fifty years the mineralogy and crystal chemistry of the materials called asbestos have been refined leading to better identification through new and more sensitive techniques. The health aspects of the exposure to fibrous inorganic species are also equally well determined from the anatomical to the biochemical levels. Integrating the efforts of many researchers from a diversity of disciplines from mineralogy and medicine, we can be more specific and detailed in the questions we raise. Coordinated research should add to our basic understanding of one area of disease induction and treatment: trauma related to inorganic materials.

Bone Lesions in Hadrosaurs: Computed Tomographic Imaging as a Guide for Paleohistologic and Stable-Isotopic Analysis

ABSTRACT High-resolution computed tomography (CT) scans through two fossilized lesions in hadrosaur bone guided paleohistological and stable-isotopic sampling to examine the stages and structures of bone repair in hadrosaurs. Two hadrosaur caudal neural spines from late Cretaceous bonebeds in Alberta, Canada, exhibit calluses produced during healing of traumatic fractures. In both CT scans and paleohistologic sections, these specimens display a combination of reptilian and non-reptilian characteristics in dinosaurian skeletal repairs. In one specimen the callus is dominated by a trabecular lattice that lacks signs of remodeling. Trabeculae in this callus are distinctively textured by clusters of densely packed, randomly oriented lacunae, two orders of magnitude larger than typical osteocyte lacunae and reminiscent of hypertrophic chondrocytes in cartilage of reptiles. The lattice represents early mineralization of callus tissue, and it preserves a &dgr;18O value in mineral phosphate 0.6‰ lower than adjacent non-pathologic cortex, suggesting that the repair site was ∼2.5°C warmer than uninjured tissue. The elevated temperature results from locally enhanced cellular activity around the fracture, a common consequence of bone injury in vertebrates. In the second specimen, the callus has been extensively remodeled, with several areas transformed to dense secondary Haversian bone typical of modern birds. Stable oxygen isotopes in bone phosphate of this callus show no isotopic offset, indicating that this injury had progressed further through the healing process before the animals death. High-resolution CT scans reveal tissue density and structure differences between the two lesions, suggesting that this technology could eventually be used to gauge relative healing without altering unique fossil specimens.

The Web of Magnesium

Magnesium is a common and abundant element in many Earth environments, especially in serpentine minerals and the rocks associated with serpentinites. The element is also a major constituent in life forms, from bacteria to man. It is important to plants where it is uniquely situated in the chlorophyll molecules that impart the green color, and plays the dominant role in photon reception and transfer of energy essential for metabolism. The multiple roles of magnesium in biology are briefly examined to phrase questions regarding the low productivity of plants typical of serpentinite environments.

Mineralogy of Bones

Medical geology encompasses many scientific endeavors with global activities and impact, but it also includes aspects that are very personal and individual. Local environment is sampled through what is ingested and inhaled whether or not it is salubrious, marginal, or downright unhealthy. Human bodies react to the remarkable range of natural and man-made chemicals that they are exposed to every day. It is common knowledge that a range of nutrients is required, but some of the chemicals can be hazardous to our health. This chapter focuses on bones, and specifically the mineral portion in these tissues, the component essential to the functions of these organs. These discussions illustrate several attributes of the emerging field of medical geology. The scientific information outlined herein is drawn from a diversity of disciplines and expertise, from biophysical and biochemical sciences, from physicians and dentists, and from geologists, mineralogists, and engineers. This knowledge enables us to address the many individual and collective roles that minerals play in the body. A disorder that affects people on every continent, osteoporosis, is presented as an example of how information on minerals can be applied. It is only one of the possible targets of opportunity where mineralogical/geological expertise has, and continues to have, the potential to ameliorate suffering and promote better global and personal health. Selected classic and recent references are included to whet the appetite of those who will make contributions to our knowledge in the future.

Fluoride-induced changes in ashed bone mineral of growing sheep. An X-ray diffraction analysis.

Physical differences were noted in the inner and outer parts of the tibial cortex of a sheep drinking water containing 100 parts per million of fluoride. In this animals cortex and in the cortex of sheep fed one and ten parts per million, the fluoride content of the mineral was higher than that of a control sheep and higher in the outer than in the inner part of the cortex of the animals receiving fluoride. X-ray diffraction of the mineral phase after ashing demonstrated apatite in all animals and in those receiving ten and 100 parts per million, a second mineral phase, whitlockite, located in the outer cortical bone.

Fluids in human bodies and biomineralization – parallels to global water resources and reactions

The amount of surface freshwaters on Earth is remarkably small considering the human population needing drinking water to survive and to ensure water in their bodies is at that very important locale where cells operate, the transcellular fluid. Like the fluid in and on the planet, body fluid is highly mobile. Cells that cause biomineralization contain and function within a fluid fraction. The mineral bioapatite is constructed by these cells in an environment containing a small amount of transcellular fluid.