ALKALINE
al•ka•line |
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- alkaline minerals have high levels of sodium and potassium metals. |
BASALTIC
ba•sal•tic |
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- refers to basalt - a basic volcanic rock; a hard, dense, dark volcanic rock often having a glassy appearance. |
BIREFRINGENCE
bi•re•frin•gence |
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- Light travels through a crystal which exhibits birefringence in two different directions and with two different velocities (one fast, one slow) producing two different light rays. By placing a piece of paper with writing underneath a piece of Optical Calcite - one can observe two images of the writing slightly offset from each other. This is caused by the two types of light rays produced by the mineral. |
CHALCEDONY
chal•ce•dony |
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- a very coarse grained lustrous semitransparent type of silica, Si02, which may be colored by impurities. It generally occurs as a deposit in cavities in lava and sedimentary rocks. |
CHERT
chert |
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- an extremely hard, white, gray or black type of chalcedony that occurs as masses or layers in limestone. The nodular form is known as flint. |
CLEAVAGE
cleav•age |
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- the tendency of some minerals to break along planes of weakness in the molecular structure. |
DIATOMITE
dia•to•mite |
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- a very fine-grained siliceous rock consisting of the skeletal remains of diatoms. They are formed under both freshwater and marine conditions. |
DIKE
dike |
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- a tabular body of igneous rock that has been injected while molten into a fissure of another rock |
EVAPORITES
e•vap•o•rites |
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- Sedimentary rocks formed by the evaporation of sea or lake water. |
FELDSPAR
feld•spar |
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- are the most common and abundant mineral in igneous rocks. They are the most important type of rock forming minerals. |
FLUORESCENCE
fluo•res•cence |
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-the emission of electromagnetic radiation, especially of visible light, stimulated in a substance by the absorption of incident radiation and persisting only as long as the stimulating radiation is continued. |
GEODE
ge•ode |
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- a hollow, usually spheroidal rock with crystals lining the inside wall. |
HYDROTHERMAL
hy•dro•ther•mal |
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- The formation of minerals by hot solutions rising from a cooling magma. |
IGNEOUS
ig•ne•ous |
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- a rock formed by the crystallization of magma or lava. See also our Science page - Igneous Rocks |
INTRUSION
in•tru•sion |
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- the forcible entry of molten rock or magma into or between other rock formation |
IRIDESCENCE
ir•i•des•cence |
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- exhibition of rainbowlike colors on a surface. It usually results from interference when light composed of different wavelengths is reflected from the superficial layers of organic or inorganic substances |
METAMORPHIC
met•a•mor•phic |
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- refers to mineralogical and chemical changes which takes place in the solid state in preexisting sedimentary or igneous rocks because of new physical or chemical conditions. See also our Science page - Mineral Associations |
MICROCRYSTALLINE
mi•cro•crys•tal•line |
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- having a crystalline structure visible only under a microscope. |
OXIDATION
ox•i•da•tion |
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- is a weathering process between rocks and atmospheric oxygen. Usually the oxygen is dissolved in water which comes into contact with the rock. |
PEGMATITE
peg•ma•tite |
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- a coarse variety of granite occurring in dikes or veins. |
PIEZOELECTRIC
pi•e•zo•e•lec•tric |
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- the property of certain crystals that causes them to produce voltage when a mechanical pressure is applied to them such as sound vibrations. This technique is used to build crystal microphones, phonograph cartridges and strain gauges, all of which turn mechanical movement into voltage. |
POLARIZING
po•lar•iz•ing |
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- cause to vibrate in a definite pattern |
QUARTZ
quartz |
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- one of the most important rock-forming minerals, consisting of silicon dioxide. It crystallizes in the trigonal system, and occurs as sand and as deposits of highly transparent colorless crystals (rock crystal), sometimes tinted by impurities. These give rise to the varieties known as rose quartz and smoky quartz, as well as to amethyst and citrine. Quartz is also the basis of cryptocrystalline minerals such as agate, chalcedony, jasper and opal. Quartz is a component of granite and other acid igneous rocks: it also occurs in metamorphic rocks (quartzite) and some sedimentary rocks (sandstone). It has many industrial uses, mainly in the manufacture of abrasives and glass. |
SILICA
sil•i•ca |
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- Silicon Dioxide, Si02. It is the chief mineral in chert, diatomite, and sand, and in crystalline form it makes up all the varieties of quartz and other silica minerals. |
SPHERULITES
spher•u•lites |
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- Spherical crystalline bodies of radiating crystal fibers found in vitreous volcanic rocks. |
TABULAR
tab•u•lar |
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- having a flat surface |
VEIN
vein |
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- an irregular tabular igneous intrusion |
VITREOUS
vit•re•ous |
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- having the nature of glass; glassy |
