II
Abstract
A crystal with a blue needle phenomenon has appeared on the market, known as "blue
needle crystal", which is loved by many jewelry collectors. Blue needle crystals are more
common in white crystal clusters, and blue needle-like inclusions with obvious colors can appear
inside blue needle crystals in bright light or sunlight. Inside the blue needle crystal, you can see a
series of blue needles intertwined, and the inside is like a blue feather, so it is called "angel
wings" in the market. Inside the blue needle crystal, there are also two sets of blue needles that
are crossed in different directions, like a pyramid. At the same time, at a certain angle, the blue
needle appears flaky, some angles are needle-like, and some small particle-like transparent
mineral crystal inclusions appear. The samples in this article are recorded as Q-1
(1.2cm×0.7cm×2.2cm) and Q-2 (1.5cm×1cm×1.7cm) in the East China Sea Crystal Market, all
of which are colorless, transparent, glassy crystal columns. Study the basic characteristic density
of blue needle crystal gemology with conventional gemological instruments. Using Fourier
infrared spectrometer, infrared reflection method to analyze the composition of the sample,
determine the correctness of the sample, and determine the sample composition according to the
vibration of different groups in the infrared spectrum. In the infrared spectroscopy test, the blue
needle crystal appeared in the absorption peak of 1184cm-1
and 1114cm-1
, and the Si-O
telescopic vibration band within the circumference of 900-1200cm-1 was consistent with the
range of the colorless crystal in the range of Si-O telescopic vibration band in the range of
900-1200cm, which was consistent with the characteristic absorption peak of colorless crystal in
the infrared reflection spectrum. By Raman spectroscopy test, the Raman profile of the blue
needle crystal inclusion has the characteristic peak positions of 126cm-1
, 206cm-1
, 264cm-1
,
353cm-1
, 463cm-1
, 479cm-1
, 1088cm-1
, 1458cm-1. Among them, the strong and sharp Raman
displacement of the blue needle crystal 463cm-1
is more consistent with the strong and sharp
Raman displacement at the crystal 466cm-1. The blue needle crystal sample was thinly ground,
the sample thickness was 0.03mm, the sample was not covered with coverslips, the sample Q-1
was cut in the direction of the parallel optical axis, and the sample was cut in the direction of the
vertical optical axis of the sample Q-2. With polarized microscope sheet identification, blue
needle crystal inclusions appear inside the two sets of parallel arrangement of cross inclusions,
there are many extremely fine holes, these two groups of needle-like inclusions are grown
according to a certain law, blue needle crystal growth process due to the blue needle crystal
inside the ultra-microscopic particles, gas-liquid inclusions, in the fissure and cavity appears
extremely fine inclusions, in the perspective of natural light appears Rayleigh scattering
