The wiki claims turning it into a captivating treasure isn’t worthwhile Mountain-sherd - Official Sunless Sea Wiki
The Interactions table it provides as evidence, is largely full of ways to GAIN a mountain sherd. as far as i can see, very few ways to actually use it, mostly the father’s bones ambition (which im not doing) and the carnelian exile’s questline. it’s not clear on how many that requires, can anyone specify?