Secret-sacred

2001, Moira G. Simpson, Making Representations: Museums in the Post-Colonial Era Most major Australian museums now hold secret/sacred material in a separate storage area, with access restricted to specified curatorial staff and to those members of the relevant Aboriginal community who have the right to view such material.

Source: wiktionary

2004, Robert Tonkinson, Individual Creativity and Property-Power Disjunction in an Australian Desert Society, in Property and Equality: Ritualization, Sharing, Egalitarianism While it is true that, in some areas, women possessed secret-sacred knowledge and rituals, nowhere was this corpus considered more important for social reproduction than that held by mature men, who claimed they exercised their responsibilities for the society as a whole.

Source: wiktionary