FRANKLINITE, a member of the spinel group of minerals, consisting of oxides of iron, manganese and zinc in varying proportions, (Fe, Zn, Mn)"(Fe, Mn)2"'O4. It occurs as large octahedral crystals often with rounded edges, and as granular masses. The colour is iron-black and the lustre metallic; hardness 6, specific gravity 5.2. It thus resembles magnetite in external characters, but is readily distinguished from this by the fact that it is only slightly magnetic. It is found in considerable amount, associated with zinc minerals (zincite and willemite) in crystalline limestone, at Franklin Furnace, New Jersey, where it is mined as an ore of zinc (containing 5 to 20% of the metal); after the extraction of the zinc, the residue is used in the manufacture of spiegeleisen (the mineral containing 15 to 20% of manganese oxides). Associated with franklinite at Franklin Furnace, and found also at some other localities, is another member of the spinel group, namely, gahnite or zinc-spinel, which is a zinc aluminate, ZnAl2O4, with a little of the zinc replaced by iron and manganese. FRANK-MARRIAGE (_liberum maritagium_), in real property law, a species of estate tail, now obsolete. When a man was seized of land in fee simple, and gave it to a daughter on marriage, the daughter and her husband were termed the donees in frank-marriage, because they held the land granted to them and the heirs of their two bodies free from all manner of service, except fealty, to the donor or his heirs until the fourth degree of consanguinity from the donor was passed. This right of a freeholder so to give away his land at will was first recognized in the reign of Henry II., and became up to the reign of Elizabeth the most usual kind of settlement.