Rock Key, Selection, and Splitting

The Rock Identification- A Dichotomous Key- Interactive PDF (web version: Rock Key)

List of rock types


The rock cycle diagram

USGS Mineral Resources On-Line Spatial Data Map (select Geology/geologic map, and any other desired data– sample below)


Mineral and Rock Identification Made Easy

North East rock types/examples:


Some rocks split better than others. The quality of splitting is based on the grain or crystalline structure and cleavage planes that should be followed/mimicked when drilling- cleavages are perfect, imperfect, distinct, good, fair, and poor.  The difficulty of splitting is formally is described as easy, hard, and difficult to produce. 


Planes Type
1 Basal or pinacoidal
2 Prismatic
3 at 90 degrees Cubic
3 not @ 90 degrees Rhombohedral
4 Octahedral
6 Dodecahedral

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