Checking the optical constants given in "Themicroscopique determination of the nonopaque minerals" by E. Larsen

The check was carried out using diagrams by A.K. Boldyrev. The check was carried out as follows (see article). It turned out that the discrepancies did not exceed 1/2°; in some cases, with very small ∆g and ∆р, the reading accuracy dropped to 1°, but the latter is rare. Upon inspection, large discrepancies were discovered between the values of 2 V given by Larsen and 2 V obtained from the diagrams (see article). The total of 380 minerals were tested.