Perhaps his greatest claim to fame is his association with the Holtermann Nugget, the largest gold specimen ever found, 59 inches (1.5 m) long, weighing 630 pounds (290 kg) and with an estimated gold content of 3,000 troy ounces (93 kg), found at Hill End, near Bathurst, New South Wales.

[1][4] He departed Liverpool aboard the ship Salem and reached Melbourne in August after a journey lasting 101 days.

[5] He built a large mansion, "The Towers" in North Sydney, complete with a stained glass window depicting himself and the specimen.

[9] Holtermann financed and possibly participated in Beaufoy Merlin's project to photograph New South Wales and exhibit the results abroad to encourage immigration.

Almost seventy years after Holtermann's death, more than 3,000 of the glass negatives created by Merlin and Bayliss were retrieved from a garden shed in the Sydney suburb of Chatswood.

[15] After he retired from mining, he wrote papers and devised formulae for medicines, and promoted and sold "Holtermann's Life Preserving Drops".

[2][15] He died in Sydney, Australia on his birthday, 29 April 1885, of "cancer of the stomach, cirrhosis of the liver and dropsy",[15] leaving a wife, three sons and two daughters.