Rock Identification
Rock Identification - Related Videos
09:26
Igneous Intrusive Rock
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2023
Source: Laboratory of Alan Lester - University of Colorado Boulder Igneous rocks are products of the cooling and crystallization of high temperature liquid rock, called magma. Magmatic temperatures typically range from approximately 800 °C to 1,200 °C. Molten rock is, perhaps luckily for humans, an anomaly on planet Earth. If a random and imaginary drill hole were made in the Earth, it would most likely not reach a region of truly and totally molten material until the outer core, at nearly...
07:28
Igneous Volcanic Rock
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2023
Source: Laboratory of Alan Lester - University of Colorado Boulder Igneous rocks are the products of cooling and crystallization of magma. Volcanic rocks are a particular variety of igneous rock, forming as a consequence of magma breaching the surface, then cooling and crystallizing in the subaerial environment. Magma is molten rock that typically ranges in temperature from approximately 800 °C to 1,200 °C (Figure 1). Magma itself is produced within the Earth via three primary melting...
05:36
Determining Spatial Orientation of Rock Layers with the Brunton Compass
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2023
Source: Laboratory of Alan Lester - University of Colorado Boulder Most rock units exhibit some form of planar surfaces or linear features. Examples include bedding-, fault-, fracture-, and joint-surfaces, and various forms of foliation and mineral alignment. The spatial orientation of these features form the critical raw data used to constrain models addressing the origin and subsequent deformation of rock units. Although now over 100 years since its invention and introduction, the Brunton...
14:12
Rodent Identification II
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2015
Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN Animal records must be accurately maintained to ensure that data collection is correct. Records range from maintaining information on cage cards to having a detailed database with all of the relevant information on each animal. The primary component of recordkeeping is the individual identification of research animals. There are a variety of methods suitable for identifying mice and rats. This...
10:36
Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction
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Cited by 1 •
2018
We report detailed procedures for compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus coupled with synchrotron X-radiation. Such experiments allow quantification of the stress distribution within samples, that ultimately sheds light on compaction processes in geomaterials.
FAQs
These features provide complementary clues about how a rock formed. Grain size and crystal arrangement help indicate whether minerals formed from cooling material, accumulated as sediment, or changed under pressure and heat. Layering can support sedimentary interpretation, while mineral composition and texture help separate visually similar rocks and connect identification with their formation history.
Weathering can alter the minerals, texture, and apparent condition of a rock, making its surface differ from the fresher material below. Observing weathering helps prevent identification based only on a degraded exterior and provides context for durability and strength assessments. It is especially relevant where exposed rock may experience environmental stresses during construction or service.
Petrographic examination provides microscopic information that field inspection may not reveal. By examining crystal structure and alteration, it can clarify mineral relationships, confirm an uncertain visual classification, and identify changes within the rock fabric. This added detail improves interpretation when color, grain size, or surface condition alone cannot adequately distinguish materials.
Hardness and density tests supply measurable properties that complement visual observations and mineral identification. Hardness indicates resistance to scratching, whereas density helps characterize the material’s mass relative to its volume. Used together with texture and composition, these measurements can resolve ambiguous identifications and provide engineering-relevant evidence about the material being evaluated.
Begin with field observations of color, grain size, layering, and weathering, then record the suspected rock type and relevant site conditions. Follow with hardness and density testing and examination of mineral composition. If uncertainty remains, use petrographic examination to inspect crystal structure and alteration. The combined observations support a more reliable engineering interpretation than any single test.
It is particularly valuable during site characterization and material selection for aggregates, foundations, tunnels, and slopes. Identification helps engineers relate the rock’s composition and condition to expected strength, durability, and permeability. Those properties influence whether a natural material is suitable for a planned use and how the surrounding rock mass may respond to construction stresses.
For tunnels and slopes, the identified rock type and observed condition provide a basis for anticipating behavior under construction and environmental stresses. Texture, mineral composition, layering, and weathering help explain differences in strength, durability, and permeability. This information supports safer interpretation of the rock mass and more informed decisions during site characterization and design.