Reheating events and diffusion of argon from the boundaries of the grain can result in lower Ar date.
Sometimes, when a large amount of argon has been lost, this is not possible.
Second, the sample is irradiated along with a standard of a known age. A major advantage of the argon-argon method is that the sample can be heated incrementally.
This process, known as "step heating", provides additional information on the age of the sample.
In these cases, the age of the first batch of argon released is the age of the reheating event, and the age of the last argon released is the minimum age of initial crystallization.
It is also common that only the argon released from a crystal early-on is problematic, and that a plateau is reached in the argon that is released in later stages of the analysis.
In the US, about 66% of feldspar is consumed in glassmaking, including glass containers and glass fiber.
Ceramics (including electrical insulators, sanitaryware, pottery, tableware, and tile) and other uses, such as fillers, accounted for the remainder.In ceramics, the alkalis in feldspar (calcium oxide, potassium oxide, and sodium oxide) act as a flux, lowering the melting temperature of a mixture.Fluxes melt at an early stage in the firing process, forming a glassy matrix that bonds the other components of the system together.The specific gravity in the plagioclase series increases from albite (2.62 g/cm Feldspar is a common raw material used in glassmaking, ceramics, and to some extent as a filler and extender in paint, plastics, and rubber.In glassmaking, alumina from feldspar improves product hardness, durability, and resistance to chemical corrosion.In earth sciences and archaeology, feldspars are used for K-Ar dating, argon-argon dating, and luminescence dating.