Understanding the origin of volatiles and identifying opaque phases on the surface of Mercury are important tasks to be completed to understand the planet's building blocks and early evolution. Pyroclastic deposits, typically featuring higher and steeper reflectance spectra than the global average, are a bridge connecting the two tasks. We report the first discovery of dark pyroclastic deposits on Mercury, which exhibit identical morphology and geometry with typical reddish pyroclastics but comparable reflectances to low‐reflectance materials (LRM). Two Kuiperian‐aged dark pyroclastic deposits and many potential older ones are discovered. Reflectance spectra for one Kuiperian‐aged pyroclastic deposit exhibits an absorption feature attributable to graphite, indicating incomplete exsolution of C from the pre‐eruption magma and/or a dominance of blasted country rocks in the pyroclastics. Our second Kuiperian‐aged case and also ∼12.5% of the global LRM exhibit no graphite or other absorption features, and metallic iron may be the alternative darkening phase.

中文翻译：

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近期在汞上的深色火山碎屑矿床

了解挥发物的起源并确定水星表面的不透明相是完成了解行星的组成部分和早期演化的重要任务。火成岩沉积物通常具有比全球平均水平更高和更陡的反射光谱，是连接这两个任务的桥梁。我们报道了在水星上首次发现深色火山碎屑沉积物，该沉积物具有与典型的红色火山碎屑相同的形态和几何形状，但反射率可与低反射率材料（LRM）相媲美。发现了两个库佩里安年龄的深色火山碎屑矿床和许多潜在的较旧的火山碎屑床。一种Kuiperian年龄的火山碎屑沉积物的反射光谱显示出归因于石墨的吸收特征，表明火山喷发岩浆中的C不完全从喷发岩浆中解脱出来和/或在爆破碎屑岩中占主导地位。我们的第二次Kuiperian衰变案例以及全球LRM的约12.5％没有石墨或其他吸收特征，金属铁可能是替代的变黑阶段。