Comparative Study on Petroleum-Bearing Quartz Crystals from Madagascar and Pakistan
-
摘要: 油胆水晶指含有肉眼易见、有色、具荧光效应的有机包裹体的一类水晶的统称。品质达到宝石级的油胆水晶并不多见，多以产地命名，主要有巴基斯坦油胆水晶、马岛油胆水晶(产于马达加斯加)、巴西油胆水晶等，以前两种最为常见。这两种产地的油胆水晶外观较相似，但价格差异较大，因此有必要对其产地进行区分。本文收集了马达加斯加马岛和巴基斯坦两个产地的油胆水晶原石各10颗，采用常规宝石学测试、超景深显微镜观察、激光拉曼光谱等测试方法对其进行对比研究。结果发现，两者在结晶习性与包裹体特征两方面存在差异：马岛油胆水晶的l/b(晶体长宽比)在1.9-4.4之间，属短柱状-长柱状水晶原石，而巴基斯坦油胆水晶l/b均小于1.5，属于双锥状水晶原石；马岛油胆水晶均有不发育三方双锥面(s)，而巴基斯坦油胆水晶个体中s面出现概率达40%。巴基斯坦油胆水晶中的有机包裹体主要有负晶型三相、不规则三相、黑色固相和干涸状四种类型，三相包裹体的液相部分呈浅黄色-亮黄色，长波紫外灯下发出黄白色-蓝白色荧光。马岛油胆水晶中的有机包裹体主要有负晶型三相、不规则三相、气液两相、固液两相和黑色固相五种类型，包裹体的液相部分有无色、橘黄色和橘红色，在长波紫外灯下无色及橘黄色液相会发黄白色-蓝白色荧光，而部分橘红色液相会发出红色荧光。两种产地的油胆水晶中黑色固相包裹体经拉曼光谱测试均为碳质沥青，以1 340，1 600 cm-1附近一对峰以及以2 940，3 200 cm-1附近为中心的一对弱宽缓峰为特征，其它有机包裹体由于过强的荧光干扰，未能得出有效的图谱。巴基斯坦油胆水晶中均为原生包裹体，而马岛油胆水晶中出现了多期沿愈合裂隙面分布的假次生包裹体，这可能指示马岛油胆水晶经过多期生长形成，而巴基斯坦油胆水晶仅在一期热液事件中结晶。Abstract: Gem-quality petroleum-bearing quartz is a type of quartz containing large (visible to naked eye), coloured, fluorescent organic inclusions. It is rare in the market and mostly named after the origin, including petroleum-bearing quartz from Pakistan, petroleum-bearing quartz (produced in Madagascar) from Madao, petroleum-bearing quartz from Braziletc. The first two of which dominate the market, having similar appearance but the prices differ largely. Therefore, it is necessary to distinguish their origins. In this paper, 20 samples from Madao and Pakistan (10 samples for each) were collected and studied by conventional gemmological methods, digital microscope system and Raman spectroscopy. The results showed that they have differences in crystal habits and inclusion characteristics: The I/b (the length-width ratio of the rough crystal) of petroleum-bearing quartz (produced in Madagascar) from Madao is between 1.9-4.4, indicating that they belong to the short-column to long-column quartz, while the I/b of petroleum-bearing quartz from Pakistan is all below 1.5, belonging to the bipyramidal quartz. Petroleum-bearing quartz from Pakistan has a 40% probability of showing trigonal bipyramid face(s), while petroleum-bearing quartz from Madao lacks of it. There are four types of organic inclusions in petroleum-bearing quartz from Pakistan: Negative crystal-shaped three-phase inclusions, irregular three-phase inclusions, black solid-phase inclusions and dry inclusions with craquelure-like inwall. The liquid phase is light yellow to bright yellow and emits yellow-white to blue-white fluorescence under long-wave ultraviolet light. While five types of organic inclusions were shown in petroleum-bearing quartz from Madao: Negative crystal-shaped three-phase inclusions, irregular three-phase inclusions, gas-liquid two-phase inclusions, solid-liquid two-phase inclusions and black solid-phase inclusions. The colours of the liquid phase including colourless, croci and jacinth, colourless and croci ones emit yellow-white to blue-white fluorescence under long-wave ultraviolet light, while some of the jacinth ones emit red fluorescence. Black solid-phase inclusions in both samples have been identified as bituminous by Raman spectroscopy, characterized by a pair of peaks near 1 340, 1 600 cm-1 and a pair of weak peaks centered at about 2 940, 3 200 cm-1. However, other organic inclusions could not be identified due to the strong fluorescent interference. The inclusions in petroleum-bearing quartz from Pakistan are all protogenetic, while there are different stages of pseudosecondary inclusions distributed along the healing fractures in petroleum-bearing quartz from Madao. This phenomenon may indicates that petroleum-bearing quartz from Madao was formed by multiple stages of growth, while petroleum-bearing quartz from Pakistan crystallized in only one stage of hydrothermal event.
-
Keywords:
- petroleum-bearing quartz /
- organic inclusion /
- crystal habit /
- Raman spectroscopy /
- Madao /
- Pakistan
-
![]()
图 1 马达加斯加马岛油胆水晶样品外观Figure 1. Photograph of petroleum-bearing quartz samples from Madao, Madagascar![]()
图 2 巴基斯坦油胆水晶样品外观Figure 2. Photograph of petroleum-bearing quartz samples from Pakistan![]()
图 3 马达加斯加马岛油胆水晶中的包裹体a.负晶形三相包裹体；b.不规则三相包裹体；c.气液两相包裹体；d.固液两相包裹体；e.沿愈合裂隙面分布的假次生三相包裹体；f.黑色固相包裹体Figure 3. Inclusions in petroleum-bearing quartz from Madao, Madagascar![]()
图 4 巴基斯坦油胆水晶中的包裹体a.负晶形三相包裹体；b.不规则三相包裹体；c.黑色固相包裹体；d.干涸状包裹体Figure 4. Inclusions in petroleum-bearing quartz from Pakistan![]()
图 5 长波紫外灯下的马达加斯加油胆水晶(左)和巴基斯坦油胆水晶(右)Figure 5. Petroleum-bearing quartz (left) from Madao Madagascar and petroleum-bearing quartz (right) from Pakistan under long-wave ultraviolet light -
![]()
图 1 马达加斯加马岛油胆水晶样品外观
Figure 1. Photograph of petroleum-bearing quartz samples from Madao, Madagascar
![]()
图 2 巴基斯坦油胆水晶样品外观
Figure 2. Photograph of petroleum-bearing quartz samples from Pakistan
![]()
图 3 马达加斯加马岛油胆水晶中的包裹体
a.负晶形三相包裹体；b.不规则三相包裹体；c.气液两相包裹体；d.固液两相包裹体；e.沿愈合裂隙面分布的假次生三相包裹体；f.黑色固相包裹体
Figure 3. Inclusions in petroleum-bearing quartz from Madao, Madagascar
![]()
图 4 巴基斯坦油胆水晶中的包裹体
a.负晶形三相包裹体；b.不规则三相包裹体；c.黑色固相包裹体；d.干涸状包裹体
Figure 4. Inclusions in petroleum-bearing quartz from Pakistan
下载:
计量
- 文章访问数: 811
- HTML全文浏览量: 296
- PDF下载量: 81
