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.
A hard stone, usually within the range of 7-9 on the Mohs scale agates are found in all colors of the rainbow, although green and blue are quite rare. Agate is a variety of chalcedony formed from layers of quartz which usually show varicolored bands. It usually occurs as rounded nodules or veins. Often tiny quartz crystals form within the stone and add to the beauty and uniqueness of individual stones. These crystals are called drusy (sometimes misspelled as druzy).