Granite is a plutonic rock in which quartz makes up between 10 and 50 percent of the felsic components and alkali feldspar accounts for 65 to 90 percent of the total feldspar content. Applying this definition requires the mineral identification and quantification abilities of a competent geologist.
Lava rock, also known as igneous rock, is formed when volcanic lava or magma cools and solidifies. It is one of the three main rock types found on Earth, along with metamorphic and sedimentary. Typically, eruption occurs when there is an increase in temperature, a decrease in pressure or a change in composition.
Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. These conditions recrystallize the sand grains and the silica cement that binds them together.
The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (since lava is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava, but look as if they were (such as sedimentary limestone with dissolution pitting).
Reintroducing a 1980s Danner Original The original Danner Jag debuted in the '80s as a lightweight alternative to our classic, heavy-duty hiking boots. After a few years on the trail supporting external frame backpacks and complementing denim cut-offs, the Jag was retired.