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Haggertyite is a magnetoplumbite-type structure from the Prairie Creek lamproite, Arkansas, U.S.A. It has hexagonal morphology that occurs as isolated platelets in reactions zones surrounding small mafic xenoliths in the lamproite. Composed of large cations of Barium and saturated in transitions elements like iron, manganese, copper, titanium, chromium, and nickel. Space group P63/mmc. Haggertyite is opaque with metallic luster, and does not have internal reflections. Present an irregular conchoidal fracture. Mohs hardness of 5 and density is 4.74g/cm3. It was named after Stephen E. Haggerty from the Department of Geology, University of Massachusetts.

Composition
The chemical formula of Haggertyite is Ba0.68K0.31Ti5.05Fe2+3.91Mg3+2.01Mg0.69 (Cr, Mn, Ni)0.34O19. It simplified formula is Ba[Ti5Fe+24Fe+32Mg]O19. It is saturated in transition elements like iron, manganese, copper, titanium, chromium, and nickel. The number of atoms of each metal is normalized to 19 O atoms. The Fe+2 and Fe+3 ions were calculated stoichiometrically to give charge balance in the magnetoplumbite formula AM12O19 because a direct analysis for FeO and Fe2O3 was not performed due to the small quantity of the sample size. The composition of Haggertyite is compared to that in the magnetoplumbite type minerals: Yimengite and Hawthorneite. In the case of Hawthorneite, the oxygen content was determined directly, and not stoichiometrically, as it was done with internal standard of metal and oxides. Therefore, determination of oxygen content has provided the most reliable estimate Fe+2 and Fe+3 contents. determined that more research has to be done in order to determine a more reliable formula for Haggertyite. Haggertyite shows an increase in Fe, Ti and K correlated with the Cr and Ba decrease, where the coupled substitution is given Fe+2+Ti 4+<-> 2Cr+3. Haggertyite and Hawthorneite have similar large cations (Barium 0.85 and Barium 0.68). While Yimengite has large potassium cantions of 0.71. .

Structure
The x-ray diffraction pattern of Haggertyite demonstrate hexagonal symmetry with all dimensions a=5.9 and c=23.3Å. It has the space group P63/mmc. Haggertyite is isostructural with magnetoplumbite type phases of Hawthorneite and Yimengite. These minerals present consistency in the cell dimensions, symmetry, and intensity distribution of (00l) reflections.

Haggertyite shows polyhedral structure where the small cations are distributed over five independent octahedral and tetrahedral sites. The anion layers are parallel to (001) with a mixed layer stacking sequence of (cchh’ hcchh’ h…) where the c and h represent cubic and hexagonal stacking and the h’ layers have one quarter of the O atoms substitute by the cations (Ba and K), giving compositional layers of AO3.

Physical Properties
Haggertyite exhibits, hexagonal crystals occurring in thin platelets with a maximum size about 100 μm, an irregular conchoidal fracture, and the forms of crystals obtained from thin sections are {001} and {100}. It is opaque with metallic luster, undistinguished with light gray in plane-polarized reflected light. Haggertyite does not have internal reflections and it is weakly birefringent in shorter wavelengths compared to Hawthorneite (Grey et al. 1998). The physical and optical properties of Haggertyite are compared to that in the magnetoplumbite type minerals: yimengite, Hawthorneite. In the Haggertyite the cleavage is not observed, whereas, in yimengite the cleavage is perfect along {0001} plane. The calculated density of Haggertyite is 4.74g/cm3 compared to yimengite 4.35g/cm3 and Hawthorneite 5.02g/cm3. The approximate mohs hardness are: Haggertyite 5, Hawthorneite 6, and Yimengite 4.

Geologic Occurrence
Haggertyite has been identified only in several specimens from Prairie Creek Lamproite, collected in the boundaries of the Crater of Diamonds State Park, Arkansas, U.S.A. Occurs in rounded, small, mafic xenoliths rocks with isolated crystals, or in small groups in the reaction zones, and Hawthorneite has been identified in one sample from Bultfotein mine in Kimberley pipe, South Africa , and Yimengite from kimberlite rocks in Venezuela .Theses three source rocks has been mined for diamonds and thus there are an important source for magnetoplumbite mineral in association with ultramafic rocks that host diamonds.

Origin of the Name
The mineral Haggertyite was named for Stephen E. Haggerty from the Department of Geology, University of Massachusetts, in recognition of his investigations and his important contributions to understanding the crystal chemistry of the titanate minerals from earth’s mantle and the mineralogy. Haggerty's major interests are in reflected-light microscopy, magnetic mineralogy, and oxidation-reduction systems relevant to magmatic ore deposits and igneous petrogenesis, but his last research projects are related with the studies of kimberlites, carbonatites, and associated alkali rocks and xenoliths.