When was the coin with the mass of 3.7 g first minted?
CREATE TABLE "table1_1307572_1" (
  "value" text,
  "diameter" text,
  "thickness" text,
  "mass" text,
  "composition" text,
  "edge" text,
  "obverse" text,
  "reverse" text,
  "first_minting" real,
  "issue" text,
  "withdrawal" text,
  "lapse" text
);
SELECT "first_minting" FROM "table1_1307572_1" WHERE "mass"='3.7 g';