Ca-bearing nepheline found in the Kajishiyama basanite, Tsuyama Basin, southwest Japan, was investigated to clarify its genesis in silica-undersaturated magmas. The basanite contains olivine and augite as phenocrysts and microphenocrysts, with Ca-bearing nepheline, olivine, augite, ulvöspinel, plagioclase, alkali feldspar, apatite and zeolites in the groundmass. Zeolites are more abundant in coarser-grained samples. The whole-rock composition of the basanite is characterised by low SiO2 and P2O5 contents and high total Fe, MgO, Na2O, K2O, Ba and Sr contents.

The Ca-bearing nepheline, ~20 μm in size, occurs in the mesostasis of the Kajishiyama basanite and contains up to 2.31 wt.% CaO and 16.75 wt.% Na2O, in contrast to nepheline from the Hamada nephelinite, southwest Japan. The approximate compositional formula of the Kajishiyama nepheline with the highest Ca content is (Ca0.467Ba0.013Na5.286K0.919□Total1.385)Σ8.070(Si0.912Al6.980Cr3+0.003Fe3+0.067 Mg0.017)Σ7.979Si8.000O32; i.e. Ne65.50Ks11.39Qxs11.22CaNe11.89.

Basanites are defined as being nepheline-normative, however they are high in normative plagioclase, the amount of which increases with fractionation of the magma. Nepheline crystallised after plagioclase, at the last stage of magmatic solidification is enriched in Ca. Such Ca-rich nepheline only forms from a magma which is high in normative plagioclase, as is the case in the Kajishiyama basanite. In contrast, Ca-poor nepheline is precipitated from nephelinitic magmas that crystallise melilite instead of plagioclase, even when Ca contents are high.

对日本西南部津山盆地 Kajishiyama 硅石中发现的含钙霞石进行了研究，以澄清其在二氧化硅不饱和岩浆中的成因。玄武岩含有橄榄石和辉石作为斑晶和微斑晶，基质中含有含钙霞石、橄榄石、辉石、长尖晶石、斜长石、碱长石、磷灰石和沸石。沸石在粗粒度样品中含量更高。玄武岩的全岩成分具有SiO 2、P 2 O 5含量低，Fe、MgO、Na 2 O、K 2 O、Ba、Sr 总含量高的特点。

含钙霞石尺寸约为 20 μm，出现在 Kajishiyama 硼硅岩的中稳态中，含有高达 2.31 wt.% CaO 和 16.75 wt.% Na 2 O，与日本西南部 Hamada 霞石岩不同。Ca含量最高的梶石山霞石的近似成分式为 (Ca 0.467 Ba 0.013 Na 5.286 K 0.919 □ Total 1.385 ) Σ8.070 (Si 0.912 Al 6.980 Cr 3+ 0.003 Fe 3+ 0.067 Mg 0.017 ) Σ7.979 Si 8.000 O 32；即Ne 65.50 Ks 11.39 Q xs 11.22 CaNe 11.89。

巴萨尼岩被定义为标准霞石，但它们的标准斜长石含量很高，其数量随着岩浆的分馏而增加。霞石在斜长石后结晶，在岩浆凝固的最后阶段富含Ca。这种富含钙的霞石仅由标准斜长石含量较高的岩浆形成，如 Kajishiyama 斜长石的情况。相比之下，贫钙霞石是从霞石岩浆中沉淀出来的，即使钙含量很高，也会结晶出黄长石而不是斜长石。