抄録
The sample has been collected in the old dump of Tanohata (Mn) Mine. This mineral is present as fibrous aggregates mixed in quartz and other manganese minerals. Our investigation shows the mineral belongs to pectolite type in which lithium and mangan play main chemical components. The late J.Ito already synthesized " Li-serandite " by his naming (Mineralogical Jurn. vol7, pp 45-65, 1972). The data of both materials are enough identical. In our conclusion this Li-Mn mineral could be the natural occurence of the synthesized material by J.Ito. The basic chemical analysis were carried out by EPMA, LA-ICP-MS analysis was done for lithium. Minor ammount of Be also has been found. X-ray powder diffraction is almost same with Ito's data. SAED pattern indicates pectolite type of crystallographical structure. A chemical formula calculated on the base of 8 oxygen: (Li 0.78, Na 0.22) 1.00 (Mn 1.86, Ca 0.03, Mg 0.09) 1.98 Si 3.01 O 8 (OH) 1.0
