Jadeite quartzite in the Dabie ultra-high-pressure metamorphic belt: a novel high-grade high-purity quartz resource

High-purity quartz (HPQ) is a critical raw material for strategic emerging industries such as semiconductors and photovoltaics, and its resource security is vital to national economic development and technological independence. Despite China’s production capacity for HPQ sand, high-quality raw ore remains heavily reliant on imports. Except for alaskite, granitic pegmatite, and hydrothermal quartz veins, quartzite has potential as an HPQ raw material but is poorly explored and understood globally. This study focuses on jadeite quartzite from the Dabie ultrahigh-pressure (UHP) metamorphic belt, a new candidate for high-grade HPQ ore, and systematically characterizes its quartz geochemical features and formation mechanism. We collected over 20 jadeite quartzite samples from Shuanghe, Xinjian and Changpu in the Dabie Mountains. The samples were prepared into thin sections and observed via optical microscopy and cathodoluminescence (CL) techniques. In-situ trace element analysis of quartz was conducted using femtosecond laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), targeting 13 impurity elements (Al, Ti, Li, etc.). NIST SRM 610/612 and quartz standard QZ-2 were used for calibration and quality control, with conservative evaluation applied for elements below the detection limit. The results show that jadeite quartzite is dominated by quartz (30–60 vol%) and jadeite, with rare mineral and fluid inclusions in quartz grains. The total impurity content of quartz ranges from 11.8 to 22.4 ppm, with average Al and Ti (key hard-to-remove impurities) contents of 2.8–7.5 ppm and 2.6–3.6 ppm, respectively. The SiO2 purity approaches or exceeds 99.998% (4N8), and these geochemical indices are comparable to or even better than international high-end HPQ sand products (e.g., IOTA-6, Drag NCA). Na and Al show a 1:1 molar positive correlation, with Na+ balancing the charge caused by Al3+ substituting Si4+ in the quartz lattice. The high purity of quartz is attributed to its crystallization from coesite retrograde metamorphism under high-pressure and medium-temperature conditions (1.8–2.8 GPa, 630–700℃) in fluid-poor environments, which inhibits impurity incorporation into the quartz lattice. This study identifies the Dabie jadeite quartzite as a new type of high-quality HPQ resource, revealing a novel genetic mechanism for HPQ formation related to UHP metamorphism. It provides a new prospecting direction for China’s HPQ resources and expands the types of exploitable HPQ deposits, which is of great strategic significance for reducing import dependence, safeguarding national HPQ resource security, and supporting the sustainable development of related high-tech industries. The considerable resource potential of this jadeite quartzite also makes it a promising strategic resource for China’s HPQ sand production.