YOU PUT WHAT IN THE FLUID INCLUSIONS?!

Applications of fundamental mineralogy have changed over the decades. Previously, fields such as economic geology and petrology made use of existing knowledge of minerals and encouraged the development of new, more sensitive means of analyzing mineral structure and chemistry. More recently, geologists have applied and expanded the basis of traditional mineralogy to address novel topics such as planetary climate history based on remote sensing of surficial mineral chemistry, processes of biological mineralization, and plausible steps in the origin of life. This talk will explore two interconnected, non-traditional applications of mineralogy. The first project is a mineralogic approach to bone that focuses on the composition, size, shape, and orientation of bone crystallites, how those mineral parameters may be interrelated, and why the parameters vary among the bones of different animals and even within the same individual. An especially intriguing question for many types of biomineralization concerns how an organic matrix directs and controls the development and characteristics of the mineral so as to form a coherent, nano-scale composite material, as in shells, bones, and teeth. In all cases, the organic matrix forms the initial template onto which the inorganic (mineral) phase precipitates. The mineralogic concept of templating led to the second project, which began as an attempt to synthetically produce the inverse of a bone or a shell, i.e., to use inorganic halite (mineral) to direct the 3-dimensional, ordered assembly of (organic) polymer nanoparticles during the evaporation of NaCl brine. The hypothesized, templated intergrowth phenomena did not occur, which led to the investigation of where the organic nanoparticles went during evaporation. Real-time observations of halite crystallization in the presence of organic nanoparticles revealed diverse encapsulation phenomena in fluid inclusions, differences in inclusion shape and volume as a function of crystal growth rate, and evaporatively pumped conduits of fluid that produced organic-enriched tufts on the halite surfaces. Traditionally, inclusions are viewed as samples of the fluid from which the mineral grew. However, we now are investigating them astrobiologically, as vessels in which to preserve (pre-)biotic organic molecules.