Hidden was very interested in natural sciences, but worked at first very successfully for the American Bank Note Company until 1884. Already in 1879, commissioned by the electrical engineer Thomas Alva Edison, he travelled extensively through North Carolina in search of economically exploitable platinum deposits. Although he discovered no platinum during the course of his investigations, he did discover in Alexander County a new variety of spodumen (named ‘hiddenite’ after him by Smith), which could be cut and polished like a gemstone. Hidden formed a stock corporation in order to technically exploit the hiddenite as well as the subsequently discovered emeralds in the area. During his career as head of the corporation, he was able to accumulate in a very short time one of the most important mineral collections. In the United States at the time, the Hidden collection was second only to the Clarence S. Bement Collection, which later went to the American Museum of Natural History in New York.

The Hidden collection is characterised by the most detailed description and cataloguing of the objects. Why Hidden sold significant portions of his collection to the Imperial Natural History Museum in Vienna is inexplicable and no elucidation can be obtained either from the American documentation available to us, or from our own archives. It is possible that the purchase of the collection, (pre-financed by Emperor Franz Josef I from the Highest Family Fund), was meant as an initial mineralogical gift to the museum. After all, the Hidden Collection comprised some 2 560 registered samples plus 646 duplicate samples.