CLEAVAGE IN A MINERAL CRYSTAL[Ref1] Cleavage in a mineral is the tendency for the crystal to split along definite  crystallographic planes as exemplified by the rhombohedron cleaved from a calcite crystal shown in Figure 1[Ref1]. These planes of weakness are present within a regular repeating array of atoms and ions within the crystal and are. . . Read More

Fracture in mineralogy is the texture and shape of the surface formed when the mineral is fractured. Fracture differs from cleavage and parting, which involve clean splitting along a plane surface, as it produces rough irregular surfaces [Ref1]. The appearance of fracture surfaces among minerals is highly varied and is a useful tool in identification.. . . Read More

Structural failure of a mineral crystal can occur by cleavage, by parting, or by fracture.  The characteristics of any of these failure modes exhibited by a mineral can be useful as tools towards its identification. In this Blog I’ll discuss the properties of cleavage and their use in identifying minerals and follow with a second. . . Read More

Along with the colors and crystal forms of minerals, their mechanical properties such as the hardness. tenacity, and habits of structural failure can be very useful tools in identifying an unknown mineral. In this first Blog on the use of mechanical properties in identifying minerals I’ll focus on hardness and describe the Moh’s Hardness Scale,. . . Read More

What Are You Curious About? I am from Wisconsin, staying in Winslow with girlfriend who is a nurse.. I just became interested in rocks and minerals and need help identifying some specimens…. thank you Your specimens are three forms of quartz, in which the crystals are of microscopic size so you can’t see their shape.. . . Read More

According to the USGS website, “A mineral is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties”. “A rock is an aggregate of one or more mineral, or a body of undifferentiated mineral matter”. For more information about rocks and minerals, be sure. . . Read More