SiO 2. One of the most common minerals in the world, quartz can be found in sedimentary, metamorphic, and igneous rocks throughout Virginia. Quartz typically appears as clear or whitish crystals within a rock such as granite.Amethyst, agate, chalcedony, chert (flint), and opal are all varieties of quartz.iO 2. One of the most common minerals in the world, quartz can be found in sedimentary, metamorphic, and igneous rocks throughout Virginia. Quartz typically appears as clear or whitish crystals within a rock such as granite.
In statistics, the standard deviation is a very common measure of dispersion. Standard deviation measures how spread out the values in a data set are around the mean. More precisely, it is a measure of the average distance between the values of the data in the set and the mean.
A related term is Variance. The variance is the standard deviation squared, and the variance is often called the mean squared error. Sample Standard Deviation Definition: The sample standard deviation is the square root of the sum of the squared differences around the arithmetic mean divided by the sample size minus 1.he variance is the standard deviation squared, and the variance is often called the mean squared error. Sample Standard Deviation Definition: The sample standard deviation is the square root of the sum of the squared differences around the arithmetic mean divided by the sample size minus 1.