Quartz is so hard that it will easily make a deep scratch in glass. Even if you press hard, a meteorite will at best only make a weak scratch mark. (Use a sharp edge of the rock.) In the photo above, the top scratch was made with a quartz crystal. The next mark was made with a piece of chert, which is another form of quartz. The two scratches at the bottom were made with ordinary chondrites (click on image for enlargement of bottom portion).
tomography. any method that produces images of single tissue planes. In conventional radiology, tomographic images (body-section radiographs) are produced by motion of the x-ray tube and film or by motion of the patient that blurs the image except in a single plane.
What Is a Hysterosalpingography? A hysterosalpingography is a type of X-ray that looks at a womanâs uterus (womb) and fallopian tubes (structures that transport eggs from the ovaries to the uterus). This type of X-ray uses a contrast material so that the uterus and fallopian tubes show up clearly on the X-ray images. The type of X-ray used is called a fluoroscopy, which creates a video image rather than a still picture. The radiologist can watch the dye as it moves through your reproductive system.