Here, we document a detailed characterisation of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.84 g) each; both came from placer deposits in the Ratnapura district, Sri Lanka. The U-Pb data are in both cases concordant within the uncertainties of decay constants and yield weighted mean 206Pb/238U ages (95% confidence uncertainty) of 530.26 Ma ± 0.05 Ma (GZ7) and 543.92 Ma ± 0.06 Ma (GZ8). Neither GZ7 nor GZ8 have been subjected to any gem enhancement by heating. Structure-related parameters correspond well with the calculated alpha doses of 1.48 × 1018 g-1 (GZ7) and 2.53 × 1018 g-1 (GZ8), respectively, and the (U-Th)/He ages of 438 Ma ± 3 Ma (2s) for GZ7 and 426 Ma ± 9 Ma (2s) for GZ8 are typical of unheated zircon from Sri Lanka. The mean U mass fractions are 680 μg g-1 (GZ7) and 1305 μg g-1 (GZ8). The two zircon samples are proposed as reference materials for SIMS (secondary ion mass spectrometry) U-Pb geochronology. In addition, GZ7 (Ti mass fractions 25.08 μg g-1 ± 0.18 μg g-1; 95% confidence uncertainty) may prove useful as reference material for Ti-in-zircon temperature estimates.

中文翻译：

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GZ7和GZ8-用于SIMS U-Pb地球年代学的两种锆石参考材料。

在这里，我们记录了两种锆石GZ7和GZ8的详细特征。两种宝石的重量均相同，均为19.2克拉（3.84克）。两者都来自斯里兰卡Ratnapura地区的砂矿。在这两种情况下，U-Pb数据均在衰减常数的不确定性和530.26 Ma±0.05 Ma（GZ7）和543.92 Ma±0.06 Ma（GZ8）的加权平均206Pb / 238U年龄（95％置信不确定度）内。GZ7和GZ8均未通过加热进行任何宝石增强。与结构相关的参数分别与计算出的1.48×1018 g-1（GZ7）和2.53×1018 g-1（GZ8）的α剂量以及（U-Th）/ He年龄438 Ma±3 Ma很好地对应GZ7（2s）和GZ8的426 Ma±9 Ma（2s）是斯里兰卡未加热的锆石的典型特征。U的平均质量分数为680μgg-1（GZ7）和1305μgg-1（GZ8）。建议使用这两个锆石样品作为SIMS（二次离子质谱）U-Pb地球年代学的参考材料。此外，GZ7（Ti质量分数为25.08μgg-1±0.18μgg-1； 95％置信度不确定度）可能有用，可作为锆石中Ti温度估算的参考材料。