John Adam Eckfeldt (June 15, 1769 – February 6, 1852) was an American worker and official during the first years of the United States Mint.

Eckfeldt served a quarter century as chief coiner, during which time the Philadelphia Mint moved to new premises.

Even after his 1839 retirement, Eckfeldt continued to perform the duties of chief coiner; his death in 1852 caused his replacement, Franklin Peale, to seek an assistant.

[2] John Jacob Eckfeldt, in his large smithy, made dies for the 1783 coinage under the Articles of Confederation authorized by Philadelphia financier Robert Morris.

[12] When the Mint's first cents (produced in 1793) were found to be excessively crude and attracted public ridicule, Eckfeldt was called upon to design replacements.

[4] In 1805, at Boudinot's request, Eckfeldt eliminated a security problem for the Mint by renting two houses adjacent to its operations, allowing it to shut an internal alley to public access.

He recalled in 1812 peering through a window to see cents coined, and Eckfeldt coming into the room to stop the work at the end of the day.

[17] On the death of the first chief coiner, Henry Voigt, in early 1814, Eckfeldt was appointed by President James Madison as successor.

After the mint moved to new premises in the 1830s, Eckfeldt discovered that the lot he had purchased had a cloud, or irregularity, on its title; he was able to clear it and sold it in 1837 for the same sum for which he had bought it.

[23] Sellers, in his memoirs, described Eckfeldt as "a man of staunch integrity, a cautious, careful, orderly and painstaking man; he was not one of the dashing, pushing, inventive mechanics, though under his care many apparently slight improvements were gradually adopted that in the aggregate amounted to a great deal in the economy of working.

[26] According to Sellers, "the giving up of almost life-long pets that had been Mr. Eckfeldt's constant care would naturally go hard, and still harder coming from another department, but as improvements gradually crept in and proved their efficiency Mr. Eckfeldt gave full credit where it belonged, and I remember him becoming quite enthusiastic over the labor saving [in the use of the Contamin portrait lathe] in duplicating working dies".

[1] After Eckfeldt's death, Peale wrote what Taxay terms a "frantic letter" to Mint Director George N. Eckert, seeking the appointment of an assistant.

Jacob Reese Eckfeldt, one of Adam's sons, was for forty years (1832–1872) Assayer of the United States Mint.

[20] Adam Eckfeldt had a taste for horticulture and owned rural property in Upper Darby Township, Pennsylvania, which was inherited by his two sons after his death.

[32] A biographical sketch of Eckfeldt, published in 1897, describes him: He was a man of large information on many subjects, possessed an inventive genius, and was enabled to introduce some excellent improvements in minting processes.

He was singularly industrious and energetic, and for his social qualities and uprightness was universally respected, and, indeed, beloved by the officers associated with him and the extended circle of his acquaintance.