The crystal structure of yeatmanite [Mn₅Sb₂] ^VI[Zn₆Mn₄(Si_3.8Fe_0.2³⁺)] ^IVO₂₈; P-1, a = 5.443(3), b = 11.683(5), c = 9.134(4)Å, α = 92.06(4), β = 101.19(4), γ = 76.34(4)°, Z = 1] from Franklin, New Jersey, has been refined to an R = 0.100 using 1881 reflections. The structure scheme proposed by Moore et al. [(1916); Neues Jahrb. Abh., 127, 47–61] was proved to be correct. The octahedral sheet consisting of 5Mn and 2Sb is sandwiched by the upper and the lower tetrahedral sheets consisting of Zn₃Mn₂Si₂, respectively. Along the a-axis, there are two rows of Si tetrahedra, one of which is surrounded by 4ZnO₄ and 2MnO₄, and the other by 3ZnO₄ and 3MnO₄. A small portion of the latter is replaced by trivalent iron. The mean distances of M–O are as follows: Sb^VI–O 2.00 Mn(1)^VI–O 2.24, Mn(2)^VI–O 2.19, Mn(3)^VI–O 2.22, Mn(4)^VI–O 2.12, Mn(5)^IV–O 2.08, Zn(1)^IV–O 2.03, Zn(2)^IV–O 1.95, Zn(3)^IV–O 1.99, Si(1)^IV–O 1.64 and Si(2)^IV–O 1.66Å.

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The first Korean ikunolite is found in Zn–Pb–Ag skarn ores from Wolam deposit of the Yeonhwa 1 mine, Republic of Korea. The average of ten microprobe analyses on nine discrete grains is: Bi 84.48, Pb 4.87, Ag 0.09, S 10.30, Se 0.01, Te 0.13, Total 99.88 wt.%, yielding the empirical formula (Bi_3.76Pb_0.22Ag_0.01)Σ_3.99(S_2.99Se_0.00Te_0.01) Σ_3.00 (basis: S + Te + Se = 3.00). The identification is substantiated by X-ray micro-diffraction and ore microscopic studies including the reflectance measurement and etch test using 20% FeCl₃ solution.
Informations due to the present finding are: 1) the first occurrence in skarn ores, 2) non-essential nature of Se and possibly Te, and 3) direct co-existence with galeno-bismutite (PbBi₂S₄), bismuthinite (Bi₂S₃) and native bismuth (Bi) to encompass the composition of the present ikunolite in the ternary system Pb–Bi–S, suggesting the necessity of such off-system component as Ag for the observed association.

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The etched track work on samples cut from different planes of apatite crystal is carried out in order to study the anisotropic etching behaviour of the crystal. The variation of the etched pit characteristics with crystallographic orientations is observed. The effect of the anisotropic etching on the age determination is reported. The etching conditions are determined for different planes using HNO₃ as the track etchant.

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Fission track ages are reported for the mineral zircon from the Coldwell Complex, Ontario, Canada using both the external detector and the population methods. Results for zircon yield a spread of fission track ages from 956.7±40 to 978.6±41 Ma. The geological history of the area is discussed in the light of fission track ages uncovered.

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Chromian pumpellyite was found in a metagabbro pebble from the Late Miocene gravel bed in the Chita Peninsula, central Japan. The mineral occurs as an aggregate of prismatic crystals with chlorite, and coexists mainly with non-chromian pumpellyite, albite and rutile. Its Cr₂O₃ content varies from crystal to crystal, and reaches 8 wt.% in maximum. Some grains are enriched also in TiO₂ (5.6 wt.% in maximum). The aggregate of chromian pumpellyite is inferred to be a pseudomorph after Cr-rich spinel.

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