Self Organizational Origin of Fibrous Texture and Twisting of Agate Quartz: Dynamic Crystallization Model

这个项目将继续研究重复性， 纹理和构图的相关自组织模式 火山玛瑙中的石英。 要研究的主要模式是 (a)由扭曲的（和 非常细和高铝）玉髓纤维与乐队由非 扭曲的（和粗和低铝）纤维，和（B）系统的 纤维化与条带的相关性，以及非纤维化与 缺乏捆绑。 我们认为纤维习性和质地 由结晶的形态不稳定性产生 前面 这种空间的不稳定性导致锋面自动地 发展出规则间隔的手指，每个手指都变成了石英， 光纤 形态不稳定产生的纤维刺穿 通过减少由另一种不稳定性（ 自催化的一个，这是时间），并通过吸积增长的 圆锥形的“袖子”，他们的轮辋被迫纳入更多的铝 比他们的中心。 这导致纤维扭曲生长。 这个项目将揭开玛瑙的动力学 结晶--一个复杂的自组织过程， 地球化学、晶体化学和岩石学意义 超越玛瑙 它还将阐明地球化学因素， 控制晶体形态和自生织构类型， 矿物质和其他低温环境。

This project is to continue work on the genesis of repetitive, associated self-organization patterns of texture and composition of quartz in volcanic agates. The main patterns to be studied are (a) the systematic interlayering of bands made up of twisted (and very fine and high-Al) chalcedony fibers with bands made up of non twisted (and coarser and low-Al) fibers, and (b) the systematic association of fibrosity with banding, and of non-fibrosity with lack of banding. We theorize the fibrous habit and texture are produced by a morphological instability of the crystallization front. This spatial instability causes the front autonomously to develop regularly spaced fingers, each of which becomes a quartz fiber. The fibers produced by the morphological instability pierce through decreasing Al contours produced by another instability (an autocatalytic one, which is temporal), and grow by accretion of conical "sleeves," their rims being forced to incorporate more Al than their centers. This causes the fibers to grow twisted. This project will unravel the dynamics of agate crystallization -- a complex self-organization process with geochemical, crystallochemical, and petrologic significance well beyond agates. It will clarify also the geochemical factors that control crystal morphology and authigenic-texture type in other minerals and other low-temperature environments.