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.
Best Answer: In probability and statistics, the standard deviation of a probability distribution, random variable, or population or multiset of values is a measure of the spread of its values. The standard deviation is usually denoted with the letter Ï (lower case sigma). It is defined as the square root of the variance. To understand standard deviation, keep in mind that variance is the average of the squared differences between data points and the mean. Variance is tabulated in units squared.