Popular media often simplifies Earth materials into idealized forms, shaping public understanding of geology. To investigate this effect, this study analyzed 202 mineral illustrations from the Pokémon Trading Card Game between 1999 and 2026. By quantifying visual characteristics through Multiple Correspondence Analysis, a dominant "universal crystal template" was identified, defined by large, transparent, high-symmetry prismatic crystals in cave environments. This representation contrasts with natural systems, where minerals commonly occur as irregular, rock-forming aggregates. Comparisons between human interpretation and AI-based identification further show that these stylized images lack sufficient diagnostic information for consistent classification. While human interpretation incorporates contextual cues, AI models rely on simplified geometric features and exhibit strong anchoring bias. These results demonstrate that widely circulated media not only simplifies geological reality but systematically reinforces visual stereotypes of minerals.