(1) Kryptonite is (numerically identical to) the mineral “sodium lithium boron silicate hydroxide” [according to the label shown in the film Superman Returns]
(2) Kryptonite is essentially fictional
(3) Sodium lithium boron silicate hydroxide is actual (and so not essentially fictional)
Chappell argues for ditching (1), but my inclination is against (2). I figure that ficitonal entities don’t literally have any properties yet alone essential ones. As I argued in “Dear Watson” there might be an attenuated sense in which fictional entities have properties in virtue of authorial intent, but they will seldom have, in this sense, the property of being represented. For similar reasons, they won’t have the property of being fictional.
One worry I have about the specific example of Kryptonite is that there is too much divergence between the AP reported substance and the various properties attributed in the Superman stories. I hoped to get around this with a chemically pure (pun!) version of the puzzle: The Puppy Crusher. From the previous comments thread:
Suppose that in a James Bond novel, a character mixes a drink that no one has ever mixed before - say itâ€™s three parts gin and one part maple syrup - and they call it â€œThe Puppy Crusherâ€. Suppose at some later date an actual bar tender mixes up three parts gin and one part maple syrup. Is it necesarily true that that drink isnâ€™t a Puppy Crusher?