Closer inspection shows this is not true. The number of naturally occurring elements is actually 98.
Technetium is an element with no stable isotopes. It is produced artificially by bombarding samples of molybdenum with neutrons for commercial and scientific uses and is widely believed to be non-existent in nature. This has turned out to be not true. Technetium-99 can be produced when uranium-235 or uranium-238 undergoes fission. Minute amounts of technetium-99 has been found in uranium-rich pitchblende.
Elements 93-98 (neptunium, plutonium, americium, curium, berkelium, and californium) were all first artificially synthesized and isolated in the Berkeley Radiation Laboratory of the University of California. They have all been found in the fallout of nuclear testing experiments and byproducts of the nuclear industry and believed to exist only in man-made forms. This also turned out to be not true. All six of these elements have been found in very small amounts in samples of uranium-rich pitchblende.
This brings the total number of naturally occurring elements to 98.
Perhaps one day, samples of element numbers greater than 98 will be identified.