Abandoned iron skarn deposit Hraničná is located 16 km NW of Jeseník, Silesia, Czech Republic. It is situated in the Staré Město Crystalline Complex, belt of high grade metamorphic rocks, which suppose to be a meta-ophiolite of the initial Cambro-Ordovican rifting. The deposit itself is formed by two stratiform magnetite-hematite bands within the marbles and quartz-rich biotite gneisses. Marbles containing silicates are rich in Zn and Pb and give evidence for sedimentary of volcanosedimentary origin of the ore accumulation. We collected several samples at the adit and +20 m levels of the mine which yielded phosphohedyphane. Mineral forms irregular aggregates up to 100 μm within the calcite-dolomite-magnetite skarn. Its average chemical formula from 7 WDS spots is (Ca2.07Sr0.03Ba0.01Mg0.02Pb3.23Zn0.01Fe0.09Al0.01)Σ5.47[(PO4)2.53(AsO4)0.03(SO3)0.01(SiO4)0.24]Σ2.81[Cl1.05F0.20]Σ1.25 based on 13 O+Cl+F. Use of the normalization to Ca1 + Ca2 = 5 and employing the charge balance could lead to the possible presence of (CO3)2- up to 0.60 apfu, resp. 3.61 hm. % CO2; this possible content do not have any effect on mineral classification. It is, therefore, fifth reported occurrence of this mineral in the territory of the Czech Republic and the Bohemian Massif.

Localities Třebíč - Borovina (GPS N 49° 12.400‘ E 015° 51.280‘) and nearby Řípov (N 49° 12.700‘ E 015° 50.850‘) are known since 19th century. They represent variegated residual rocks originated during Tertiary? weathering of marbles, dolomite marbles, calcic and magnesian skarns, quartzites and hornblendites intersected by aplites and granitic pegmatites. These rocks enveloped by the biotite gneisses and migmatites close to the contact with the Třebíč Pluton belong to the Moldanubian Zone of the Bohemian Massif. In the past, there was a short-time production of Fe-ore from the weathering zone at Třebíč - Borovina, as well as production of mineral raw-material for brickworks. Since the localities are inaccessible for a long time, we investigated 11 mineral samples of manganese oxidic minerals deposited in the museum collections (Museum Vysočina Třebíč, National Museum in Prague - Natural History Museum, Museum of the South-eastern Moravia in Zlín): 10 from Borovina and 1 from Řípov, labeled as pyrolusite, psilomelane, and wad. They usually form botryoidal black aggregates up to 20 cm in size. Powder X-ray diffraction proved the presence of the coronadite group minerals, accompanied by birnessite (one sample), kaolinite, quartz, gypsum, and minerals of the spinel and chlorite groups. Unit-cell parameters of the coronadite group minerals range as follows: a = 9.750 - 9.939 Å, b = 2.851 - 2.869 Å, c = 9.840 - 10.024 Å, and β = 88.66 - 90.77° (for the monoclinic space group 2/m). Scanning electron microscopy showed the botryoidal texture, where at least part of the zoning visible in back-scattered electrons is in fact the result of density of the mineral aggregate, alternating from massive to fibrous, sometimes with the atol microstructure. Empirical average mineral formulae, based on WDS analyses, are: hollandite from Borovina (Ba2+0.40 Ca2+0.16Mg2+0.13Cu2+0.03Zn2+0.02Pb2+0.01K+0.18Na+0.04)Σ0.98 [(Mn4+5.90Si4+0.06P5+0.04)Σ6.00 (Mn1.77Fe0.20Al0.11)3+Σ2.07] Σ8.07O16, cryptomelane from Borovina (K+0.51Na+0.04Ba2+0.20Ca2+0.09Zn2+0.05Cu2+0.03Mg2+0.02Pb2+0.02Co2+0.01)Σ0.97 [(Mn4+6.91 Si4+0.03P5+0.06)Σ7.00(Mn0.72Fe0.07Al0.06)3+Σ0.85]Σ7.85O16, and cryptomelane from Řípov (K+0.66Na+0.03Ba2+0.14Ca2+0.04 Zn2+0.03Cu2+0.01)Σ0.92[(Mn4+6.88Si4+0.03P5+0.09)Σ7.00 (Mn0.77Al0.11 Fe0.04)3+Σ0.93] Σ7.93O16. Most significant are substitutions Al3+ → Mn3+-1 and Fe3+ → Al3+-1 at the M3+ site, also Mg2+ → Ba2+-1 and Ca2+ → Ba2+-1 at the A2+ site in hollandite. Accessory minerals - baddeleyite and probable xenotime-(Y), present in the hollandite and cryptomelane aggregates, were identified only by EDS analyses.

Recently described small outcrop of the upper part of the Barnasiówka Formation yielded several manganese oxidic minerals. Outcrop at the bank of the Krnalovice Stream (GPS N 49°38.623’ E 018°14.630’) consists of Lower Turonian greenish to grey-black laminated claystone alternating with grey chert. The whole sequence is a part of the Baška facies of the Silesian Unit, Outer Western Carpathians. In the middle part of the profile occur concretional aggregates containing manganese minerals. The central pale part of these aggregates is composed of quartz (ca. 90 wt.%), albite (ca. 9 wt.%), and muscovite, the darker rim of quartz (ca. 80 wt.%), goethite (ca. 10 wt.%), illite, todorokite, plagioclase, K-feldspar, and pyrite. Occasionally, remains of Mn-rich siderite were preserved in the cores. We suppose that they are in fact weathering products of carbonate-rich silicites. Manganese oxides also enter fissures in form of thin black coatings. Powder X-ray diffraction proved the presence of todorokite, ranciéite, pyrolusite, and possible vernadite. Todorokite forms black coatings with submetallic lustre, often associating with ranciéite. Ranciéite is dark pink to pinkish-brown, with a metallic lustre. Back-scattered electron images reveal its extremely thin tabular, sometimes undulated crystals and hexagonally oriented intergrowths. Powder diffraction data are strongly affected by preferred orientation, with dominating basal reflections of 001 plane at 7.4849 Å and plane 002 at 3.7424 Å. Its average formula from nine WDS spots (Ca0.14Mg0.01Ba0.01K0.01)Σ0.17(Mn4+0.86Si0.02Al0.03Fe0.01)Σ0.92O2.00·0.88H2O (based on 2 anions, water calculated from the ratio of cation sum / H2O in the formula according to Post et al. 2008) and CaO/MnO2 ratio 9 to 12 correspond well to the published data for this phase. Ranciéite is a rather common phyllomanganate from various geological environments, but this locality represents its first unambiguous occurrence in the Czech Republic. It closely resembles the one from Polish flysch Carpathians from Nowa Wieś near Rzesów.