Geochemical and mineralogical dataset of tephra from the 2021 Tajogaite eruption, La Palma, Canary Islands

Geochemical and mineralogical dataset of tephra from the 2021 Tajogaite eruption, La Palma, Canary Islands. Description of methods used for collection/generation of data: The analytical package 4LITHORES from Actlabs laboratories was used to determine the concentrations of major and trace elements in bulk tephra samples. It combines packages 4B (lithium metaborate/tetraborate fusion and ICP-OES analysis) and 4B2 (trace elements by ICP-MS). X-ray diffraction files were acquired at the analytical facilities of GEO3BCN of CSIC by using a diffractometer Bruker D8-A25 (acquisition with Cu Kα radiation, tube voltage, and current of 40 kV and 40 mA, respectively; scans from 4° to 60° in 2θ, with a step size of 0.035°, and an equivalent counting time of 192 s per step. Mineral identification and semi-quantification were carried out with the DIFFRAC.EVA software from Bruker. The leaching experiments of tephra were conducted using batch tests. In these tests, 1 gram of each ash sample was mixed with 10 millilitres of Milli-Q Plus ultrapure water (18.2 MΩ/cm) in 14x100 mm polypropylene test tubes and shaken for 4 hours at 20 rpm. Initial (pH₀, SC₀) and final (pHf, SCf) pH and specific conductivity (SC) were measured using a HANNA HI8424 pH Meter. Leachates were then filtered through 0.45 μm PVDF syringe filters and analyzed for anions (chloride, sulfate, fluoride, nitrate, nitrite) using ion chromatography (IC) on a Metrohm 850 Professional IC AnCat – MCS system. For major and trace element analysis, a portion of the leachate was acidified with 1% HNO₃, diluted to 100 ml, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS) using an Agilent 7700X instrument. All analyses were conducted at the Technical Research Services of the University of Alicante. The spreadsheets are in CSV format UT-F8 and delimited by commas.