There isn't a single geologist credited with figuring out the origins of granite. Understanding the formation of granite was a gradual process, built upon the work of many scientists over centuries.

However, some key figures who contributed significantly to our understanding of granite include:

* James Hutton (1726-1797): Often considered the "father of modern geology," Hutton proposed the concept of the "rock cycle," which explained how rocks transform from one type to another through processes like erosion, sedimentation, and igneous activity. This laid the groundwork for understanding how granite forms through the cooling and crystallization of magma.

* Charles Lyell (1797-1875): Lyell's work on uniformitarianism emphasized that geological processes occurring in the present are similar to those in the past. He applied this principle to the study of granite, suggesting it formed through processes similar to those observed in volcanoes.

* Ferdinand von Richthofen (1833-1905): Richthofen's extensive research on the geology of China helped establish the concept of batholiths, large bodies of intrusive igneous rock, including granite, that form deep within the Earth's crust.

* Norman Bowen (1887-1956): Bowen developed the concept of fractional crystallization, a process where different minerals crystallize from magma at different temperatures. This explained the variety of minerals found in granite and how their proportions can vary depending on the cooling history of the magma.

These are just a few of the many geologists who contributed to our understanding of granite. The process of uncovering the origins of granite was a collaborative effort, involving numerous scientists working over many decades.