OSI Model - The Lower Layers The bottom four layers of the OSI model are often referred to as the lower layers: â¢ Layer-4 â Transport layer â¢ Layer-3 â Network layer â¢ Layer-2 â Data-Link layer â¢ Layer-1 â Physical layer Protocols that operate at these layers control the end-to-end transport of data
Ross-Simons' Agate Jewelry. Agate is a variety of chalcedony that comes in variety colors making it ideal for all kinds of jewelry designing. Blue agate is as expected, light blue. Moss agate is dark green, often with clear patches.Tree agate is green and white.gate: Stripes Earned by Nature. With its combination of earthiness and elegance, agate is one of the most unusual gemstones. There are many varieties of agate, including blue lace agate, moss agate, tree agate and petrified wood.
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).