You recommend uniting universities' natural-history collections at regional hubs to protect them from financial constraints (see Nature 544, 137–138; 2017). The University of Michigan in Ann Arbor was initially reluctant to do this because it would have meant transferring full ownership of its mineral collection of some 15,000 specimens and irrevocably forfeiting their scientific, historical, educational and monetary value. We chose instead to set up the Michigan Mineral Alliance, in recognition of our responsibility to the public and to donors.

The alliance was created in 2015 by a perpetual legal agreement with Michigan Technological University in Houghton (see go.nature.com/2q7c5oh). It provides a shared, collaborative model for the benefit of both institutions. The mineral collection is now housed, curated, educationally exhibited and made available for research by the A. E. Seaman Mineral Museum of Michigan Tech, after uniting it with the museum's established collection.

Responsibilities for each specimen are defined; the most important are jointly managed. Should priorities change in the future, the co-ownership scheme permits return of the collection.