The Strickland quarry pegmatite has been extensively studied by Jenks (1935), Cameron et al. (1954), and Chadwick (1958) from geological evidences; and by numerous geochronologists (see summary in Rodgers, 1952; Brookins, 1963). The Contributions of W. H. Pinson, H. W. Fairbairn, and P. M. Hurley (summarized in Variations in isotopic abundances of Strontium, Calcium, and Argon and related topics: NYO-3942. Ninth Ann. Prog. Rpt. for 1961, U.S.A.E.C., Contract AT(30-1)-1381) are of particular significance as their work indicated that the initial Sr(87/86) ratio for the pegmatite mineral isochron would be high (i.e. greater than 0.730) and thus tentatively confirm derivation from material of a previous sialic history. Brookins and Hurley (1965) found that the parent material for the pegmatite was not related to the other basement rocks in the immediate area because: (1) local systems in the Collins Hill formation were too restrictive to allow sufficient migration of material to the present pegmatite site, and (2) the initial Sr(87/86) ratios for the nearby Glastonbury gneiss (0.709) and the Maromas granite gneiss (0.712) were too drastically removed from the pegmatite intercept of 0.735 (based on Sample A4774, a primary plagioclase from the Strickland quarry pegmatite) to allow derivation, from these units. These conclusions are supported by field and petrographic evidence.