The most important thing to learn about the OSI model is what it really represents. Pretend you're an operating system on a network. Your network card, operating at layers 1 and 2, will notify you when there's data available. The driver handles the shedding of the layer 2 frame, which reveals a bright, shiny layer 3 packet inside (hopefully).
Used with permission. Agate is a variety of chalcedony, a cryptocrystalline form of quartz. Translucency, patterns of color, or moss-like inclusions may distinguish this stone from other forms of chalcedony. Agates can show a wide variety of vivid, multiple colors.
Afghan Jade: (See Jade) Agate: is the name given to a wide selection of Chalcedony, a form of microcrystalline Quartz (SiO2 - Silicon Dioxide) which is a cryptocrystalline. It is a hard stone, usually within the range of 7-9 on the Moh's scale. It is characterized by its fineness of grain and brightness of color.