Determination of iron environment and redox in heterogenous obsidians

Obsidian, a prevalent naturally occurring glass formed through rapid cooling of rhyolitic lava, holds significance in earth and material sciences, as well as archaeology. While black obsidian is widely recognized, lesser-known variants exhibit diverse colors such as green, blue, red, brown, and silver, whith often heterogeneous mixing areas. Iron, a key component in obsidian, plays a crucial role in coloration. In black obsidian, dispersed iron nanocrystals contribute to its distinct color and rheological properties To unravel the relationships betwwen iron environment/redox and color/rheological properties, nano-XANES emerges as a crucial tool, enabling the investigation of iron speciation at the nanoscale. This approach aims to discern the precise environment, redox state of iron, and its impact on color variation in crystallized and non-crystallized areas of heterogeneous obsidians.

黑曜岩（Obsidian）是一种由流纹岩熔岩快速冷却形成的常见天然玻璃，在地球科学、材料科学以及考古学领域均具有重要研究价值。尽管人们对黑色黑曜岩较为熟知，但其他小众变种则呈现出绿、蓝、红、棕、银等多样色泽，且常存在非均质性混合区域。铁是黑曜岩的关键组成成分，对其色泽形成起着至关重要的作用。在黑色黑曜岩中，分散的铁纳米晶体是其独特色泽与流变学特性的成因之一。为阐明铁的赋存环境/氧化还原状态与色泽、流变学特性之间的关联，纳米X射线吸收近边结构谱（nano-XANES）成为了关键研究工具，可实现纳米尺度下铁的化学形态分析。该研究方法旨在明确非均质性黑曜岩的结晶与非结晶区域内铁的精确赋存环境、氧化还原状态，以及其对色泽变化的影响。