混合岩化型刚玉的产出特征——以河北阜平刚玉为例

Occurrence characteristics of the migmatite corundum:A case study of corundum from Fuping,Hebei Province

以河北阜平地区刚玉为例,对混合岩化型刚玉的产出特征和成因进行了论述。采用矿物学、岩石学和地球化学等研究方法,详细描述了阜平刚玉的矿物伴生组合、矿物之间的关系、结构、矿物形成的先后顺序等,并探讨该区刚玉形成机理。该处刚玉的粒度普遍较大,其伴生矿物主要有钾长石、斜长石、黑云母、白云母、夕线石、金红石、绿泥石、磁铁矿、钛铁矿、磷灰石等。根据岩相学特征推测该处刚玉是在片麻岩发生混合岩化过程中,形成富铝质的熔浆结晶而成。讨论了混合岩化型刚玉的宝石学意义,该类刚玉部分可以达到宝石级,但很难达到精品级。若进行规模开发利用,可能需要进行有针对性的优化处理。

The corundum in Fuping area of Hebei Province was taken as the studied object to probe into the occurrence characteristics and genesis of migmatite corundum.The mineral paragenetic association,texture and paragenetic sequence of minerals of corundum were investigated by means of mineralogy,petrology and geochemistry,and the formation mechanism of corundum in this area was discussed.The size of the corundum is generally large,and the associated minerals are mainly K-feldspar,plagioclase,biotite,muscovite,sillimanite,rutile,chlorite,magnetite,ilmenite,and apatite.According to petrographic characteristics,it is inferred that the corundum was formed by crystallization of aluminum-rich magma in the process of migmatization.The gemological significance of the migmatite corundum was studied,and the result shows that the migmatite corundum can reach the gem grade,although it is difficult for this mineral to achieve the fine grade.The large-scale development and utilization of this mineral should implement targeted improvement and treatment.