Ví dụ về quartz

• A pure quartz reagent blank and several certified geological reference standards, as well as internal laboratory standards, were analysed with these samples.

• It is typically defined by the shapepreferred orientation of mica and elongated quartz grains.

• The vesicles are filled with calcite, chlorite, quartz and carbon.

• Furthermore, both the tube and the coil are surrounded by the tube cooling, which protects the quartz tube from overheating.

• The c. 25 m of purple, fine-grained sandstones below include quartz-arenitic intercalations and have an essentially calcareous matrix.

• Other alteration products are chlorite, sericite, quartz and opaque minerals.

• The newly crystallized quartz grains are characterized by elongate crystals oriented oblique to the shear band margins, defining a typical grain-shape foliation.

• The presence of quartz-filled microcracks in feldspar crystals suggests that deformation continued during cooling and crystallization.

• The features result from initial growth of the quartz grain, partial resorption (dissolution) during a period of disequilibrium, then further growth to form the mantle.

• The quartz ribbons display strong undulose extinction and locally well-developed core-and-mantle microstructures.

• The quartz aggregates show a crystallographic preferred orientation.

• Quartz-feldspar ribbons and aggregates define a mineral stretching lineation.

• These are infilled by aggregates of fibrous quartz and actinolite that are aligned parallel to the macroscopic mineral lineation.

• It is well cemented by microcrystalline quartz, and was the hardest of all samples to hammer in the field.