A Simple Method to Separate Quartz and Feldspar and its Application to TL/OSL Methods

In the dating of sediments by luminescence methods, to obtain a sample the purest possible as to its mineralogy determines the rest of the analytical procedures. The isolation of the sample minerals is a critical stage due to the impossibility of quantifying the relative contributions to the dose from the different minerals. In this paper we propose a non chemical method to isolate quartz from feldspar extracted from different aeolian and fluvial sediments. Grinding together quartz and feldspar grains in an agate mortar results in crushing the feldspar fraction due to its smaller hardness. Later sieving of the grinded mixture enables simple separation of both fractions. Then it is possible to save the feldspar fraction for later analyses instead of losing it as it occurs when using acid etching. Also, we study the evolution of the feldspar abundance along different purification steps with acid etching or grinding with two numerical indexes. We conclude that the grinding procedure can be introduced in the purification methods as an effective way to separate quartz from feldspar. Nonetheless, it is not an standalone procedure to obtain pure quartz and must be combined with chemical methods when the sample is rich in feldspar minerals.