The essential oil coming from the rind of the mandarin orange also called tangerine. In general, the main component of citrus peel oils is limonene (80-97%), a super common fragrant ingredient that makes everything smell nice (but counts as a frequent skin sensitizer).
Other than that, citrus peel also contains the problematic compound called furanocoumarin that makes them mildly phototoxic. In general, the sweeter the citrus, the less it contains, so tangerine peel contains less of it than some other citruses (like bergamot or lime), but still, be careful with it especially if it is in a product for daytime use.
Show me some proof
- Dugrand, Audray, et al. "Coumarin and furanocoumarin quantitation in citrus peel via ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS)." Journal of agricultural and food chemistry 61.45 (2013): 10677-10684.