FEATURE ARTICLES "Raindrop" turquoise is a recently recognized and characterized pattern with a saturated coloration resembling raindrops. This material is very rare but popular in the Chinese gem trade. This paper investigates the differences among the raindrops, veins, and substrates (the matrix portion) of turquoise with this unique pattern using Xray diffraction, electron probe micro-analysis, laser ablation-inductively coupled plasma-mass spectrometry, and micro-spectroscopic techniques

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... man, FTIR, and UV-Vis). The raindrops and veins were identified as mixtures of turquoise and fluorapatite, which were distinct from the substrates. Nearly pure fluorapatite and turquoise were also discovered in the veins. The color origin of the brownish yellow raindrops and substrates are discussed, as well as the formation mechanism of the raindrop pattern.