Weathered granite (feldspathic, iron-stained granite)

Light gray to off-white, with pink-red and yellow-brown patches caused mainly by iron oxidation and weathering. The surface appears granular and crystalline, with interlocking mineral grains rather than sedimentary layers. Typical granite hardness is about Mohs 6–7; luster is generally dull to vitreous on fresh quartz and feldspar surfaces. Granite has no consistent cleavage as a rock, although individual feldspar grains show cleavage. Typical specific gravity is approximately 2.63–2.75.

Granite forms when silica-rich magma cools slowly deep within the continental crust, allowing quartz and feldspar crystals to grow. The reddish and brown areas likely represent oxidation of iron-bearing minerals or alteration along fractures. The rounded shape suggests transport and abrasion in a stream, beach, or glacial deposit. The rock could range from Precambrian to much younger in age; its age cannot be determined from the image alone.

Common granite is used as crushed stone, aggregate, road material, building stone, paving, countertops, monuments, and landscaping rock. This individual weathered specimen has little commercial value but may be suitable for a basic rock collection.

Granite is a coarse-grained intrusive igneous rock and is the typical rock of many continental crustal batholiths. Pink coloration commonly comes from potassium feldspar, while rusty red and yellow staining commonly results from oxidized iron minerals. A polished or freshly broken surface would show the mineral grains more clearly than this weathered exterior.

In the field, look for visible interlocking grains of translucent or gray quartz, white or pink feldspar, and darker mica or amphibole. Granite is generally hard enough to scratch glass and does not fizz vigorously with dilute hydrochloric acid. A fresh fractured surface, hand lens, streak test, hardness test, and specific-gravity measurement would help distinguish it from quartzite, gneiss, arkose, or altered volcanic rock. Common occurrences include continental batholiths and granitic terrains worldwide, including North America, Europe, India, Australia, and East Asia.