The chemical formula of mineral Avicennite is indicated by Tl2O3. This mineral is usually found in the weathered zone of a hematite-calcite vein cutting banded marmorized and silicified limestones near a granite-gneiss contact, near Dzhuzumli, Tadzhikistan. Mineral Avicennite is most commonly found at its type of locality near the village of Dzhuzumli, Mt. Zirabulaksk region, […]

The upper polar is also called analyzer. This is usually located above the objective lens of the petrographic polarizing microscope and is mounted on a side or pivot to that it can be easily inserted or removed from the optical path. Analyzer is usually constructed of a piece of optical quality polarizing film, although Nicol […]

The lower polar, condensing lenses, aperture diaphragm, auxiliary condensing lens, and one or more filter holders are the principal parts of the substage assembly. The assembly is most commonly mounted in a mechanism that would allow it to be raised or lowered anytime the observer wish.
 
            Most modern microscopes have lower polar. This lower polar […]

The oculars or the eyepieces of the microscope are the lenses that slide into the upper end of the petrographic polarizing microscope tube. These oculars are used to magnify the image provided from the objective lens and it also focuses the light so that the human eye can accept it. Many microscopes come equipped with […]

The primary magnification of the optical system is provided by the objective lenses. Objective lenses are, in effect, the heart of the microscope. Some simple microscopes, particularly most student model microscopes are equipped with three objectives having magnification of about 2.5X, 10X, and 40X. These objective lenses are either detached and interchanged by releasing a […]

By raising or lowering the stage, or by raising or lowering the microscope tube, by means of a screw or gear mechanism, focusing is accomplished. This focusing mechanism is usually provided for by both coarse and fine focusing. The rapid changes in the distance between the objective lens and the stage, is controlled by the […]

The Bertrand lens is a small lens, which is found just below the ocular. This lens is also called Amici-Bertrand lens. This Bertrand lens is mounted on a pivot or slide for the purpose that it can be easily introduced or removed from the optical path. The function of this type of lens is to […]

For the insertion of accessory or compensator, a slot is usually provided immediately above the objective lenses. The usual accessory plate of a petrographic microscope includes quartz wedge, gypsum plate, and mica plate. Each of these accessories consists of a metal or plastic frame with the optical element mounted in a hole or slot in […]

Petrographic polarizing microscopes must be kept as clean and dust free as possible. These polarizing microscopes should be picked up by the base and by the arm only. They should never be picked up by microscope tubes, stage or substage. More importantly, the lenses must never be touched. When cleaning the lenses, great care should […]

There are several other additional equipments for petrographic polarizing microscopes. Among these are the mechanical stage, the spindle stage, and the universal stage.
The one that is mounted on the stage of the microscope and grasps a slide so that the slide can […]