Petrography lower if wholly or partly vitreous. The specific gravity of the more common rocks range from about 2.5 to 3.2. Archaeologists use petrography to identify mineral components in pottery. This information ties the artifacts to geological areas where the raw materials for the pottery were obtained. In addition to clay, potters often used rock fragments, usually called "temper" or "aplastics", to modify the clay's properties. The geological information obtained from the pottery components provides insight into how potters selected and used local and non-local resources. Archaeologists are able to determine whether pottery found in a particular location was locally produced
What Is Life love song – perhaps a "lovingly crafted paen" to Harrison's wife Pattie, as Alan Clayson puts it – or a devotional song like many of Harrison's compositions. Ian Inglis writes that the song title suggests a "philosophical debate about the meaning of life", yet its rendering as ""what is my life"" in the choruses "reshapes [the meaning] completely". Theologian Dale Allison finds no religious content in "What Is Life" but notes the "failure of words to express feelings" implied in the opening line (""What I feel, I can't say""), a recurring theme of Harrison's spiritual songs such as "That Is