Curium is an element that currently exists only as a result of technology. Curium can be created in research reactors by bombarding other actinides with neutrons. Unlike the heaviest and most difficult to create elements, which must be created through high energy bombardment of two nuclei, the process of creating Curium is relatively easy. As such, relatively large quantities, in the kilogram range, can be produced. All isotopes of curium are strong alpha particle emitters, most with very short half-lives, so that any usage of curium would be confined to nuclear research, and of course handling any would be very difficult.
Despite its rare nature and difficult of manufacture on earth, Curium could be found to be "naturally" occurring, although not for very long. One isotope of Curium, Cm-247, has a half-life of 15 million years, while another, Cm-248, has a half-life of 340,000 years. While it is possible that much heavier elements than Curium could be synthesized in a supernova, the next longest-lived isotopes after these two isotopes are three isotopes of the next two heaviest elements, Berkelium and Californium. These isotopes have half-lives on the scale of a few hundred to a thousand years. While this is actually not short lived by the standards of such heavy elements, it is still too short lived to take part in geological processes.
Depending on exact models of planetary formation, the two longest lived isotopes of Curium would have time to be trapped inside of larger bodies and have their heat incorporated, rather than lost into space. After undergoing decay, they would eventually become isotopes of Uranium, and much later, Lead. Of course, not much Curium is probably produced inside even a supernova explosion: if we look at the relatively tiny amount of Uranium produced, and then imagine the uphill process of driving more mass and energy into it, the amount is probably vanishingly small.
However, as more research is done into early solar system formation, and more information is gained about exoplanets, it may turn out that the presence of these two isotopes makes a meaningful difference in early planet formation, and enables geological bodies that would otherwise be too small for it.
Thus, one of the periodic table's lesser curiosities may be a very important property of geological properties that have shaped the world we live in, as well as other possible worlds.