Overview

quartz

Return to overview »

You are looking at 1-20 of 132 entries

  • Type: Overview Page x
clear all

View:

accessory mineral

accessory mineral  

A mineral phase within a rock whose presence does not affect the root name of the rock. For instance, the root name ‘granite’ is defined by the presence of quartz, alkali feldspar, and mica. These ...
accessory plate

accessory plate  

In optical microscopy, a plate used to determine the optical properties of minerals. Quartz, mica, and gypsum are the common minerals used to determine the slow and fast vibration directions that ...
ACF diagram

ACF diagram  

A three-component, triangular graph used to show how metamorphic mineral assemblages vary as a function of rock composition within one metamorphic facies. Besides SiO2, the five most abundant oxides ...
acid rock

acid rock  

An igneous rock that contains more than 60% silica by weight, most of which is as silicate materials, with the excess of about 10% as free quartz. Acid rock is low in magnesium. Acid rocks tend to be ...
adamellite

adamellite  

A rock of granitic composition (see granite) characterized by the presence of quartz, plagioclase feldspar, and potassic feldspar (see alkali feldspar) accompanied by biotite and/or hornblende. The ...
AFM diagram

AFM diagram  

A three-component, triangular graph used to show how metamorphic mineral assemblages vary as a function of rock composition within one metamorphic facies. Besides SiO2, the five most abundant oxides ...
agate

agate  

Reference type:
Overview Page
A hard gemstone used in the construction of spatula blades. They are used for mixing tooth-coloured materials because of their resistance to abrasion and their ability not to cause discoloration of ...
allogenic

allogenic  

Applied to minerals, or other components of a rock, that have been derived from pre-existing rocks and transported some distance to form part of the present unit; e.g. quartz grains in a sandstone. ...
amethyst

amethyst  

Reference type:
Overview Page
The purple variety of the mineral quartz. It is found chiefly in Brazil, the Urals (Soviet Union), Arizona (USA), and Uruguay. The colour is due to impurities, especially iron oxide. It is used as a ...
amphibolite

amphibolite  

A medium-grained, dark-coloured, regional metamorphic rock composed of hornblende and plagioclase with minor epidote, sphene, biotite, and quartz. The rock may show a well-developed planar or linear ...
amygdale

amygdale  

; adj. amygdaloidal)Spheroidal, ellipsoidal, or (literally) ‘almond-shaped’ cavity or vesicle within a lava, filled with secondary minerals, e.g. calcite, quartz, or zeolites.
andesite

andesite  

A fine-grained volcanic rock. The andesite line is the boundary between the rocks of the oceanic crust and islands and the rocks of the continental crust in a circum-Pacific belt; the boundary ...
aplite

aplite  

A light-coloured, fine-grained, equigranular igneous rock composed of subhedral to anhedral grains of quartz and alkali feldspar, and found as late-stage veins in granite bodies. The quartz–alkali ...
arenaceous

arenaceous  

Sandy in texture, or applied to rocks composed of cemented, usually quartz, sand. Arenaceous rocks include quartzites and greywackes.
arkose

arkose  

An arenaceous rock that contains quartz and 25 per cent or more of feldspar. The feldspar is easily des-troyed during transportation or chemi-cal change, and the implication is that arkoses were ...
arsenopyrite

arsenopyrite  

Mineral, FeAsS; sp. gr. 5.9–6.2; hardness 5.5–6.0; monoclinic; silver-grey to white, often with a tarnish; dark greyish or black streak; metallic lustre; crystals prismatic, often striated, can also ...
augen-gneiss

augen-gneiss  

A medium- to coarse-grained, banded, regional metamorphic rock composed mainly of quartz and feldspar with hornblende and mica also present in variable quantities, and characterized by large ovoidal ...
barite

barite  

A mineral, BaSO4, which may form a solid solution series with celestite (SrSO4); sp. gr. 4.3–4.6; hardness 3.0–3.5; orthorhombic; colourless to white, often tinged yellow, brown, blue, green, and ...
calcarenite

calcarenite  

Calcareous sediment in which a high percentage of the clasts can be of quartz within a calcareous matrix or, more generally, a clastic limestone in which both clasts and matrix are calcareous. ...
cassiterite

cassiterite  

Mineral, SnO2; sp. gr. 6.8–7.1; hardness 6–7; tetragonal; usually reddish-brown to nearly black, but it can be yellowish and ruby; white to grey streak; adamantine lustre; crystals often pyramidal ...

View: