Coquina

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coquina

[kō′kē·nə]
(invertebrate zoology)
A small marine clam of the genus Donax.
(petrology)
A coarse-grained, porous, easily crumbled variety of limestone composed principally of mollusk shell and coral fragments cemented together as rock.

Coquina

 

limestone consisting primarily of the shells of marine animals or fragments of shells. Coquina usually forms in the littoral or sublittoral zones. Depending on the shells of which it is composed, coquina is subdivided into brachiopod, gastropod, ostracod, and other types. It corresponds to gravelpebble sediments in granulometric composition. Coquina has a very high porosity of 22–60 percent. Its specific gravity is 1,100-2,240 kg/m3, and its heat conductivity coefficient is 0.29-0.99 watt/(m-°K), or 0.25-0.85 kcal/(hr-m-°C). Its breaking point upon compression is 0.4-28 MN/m2 (4-280 kg/cm2).

Coquina is easily sawed, trimmed, and worked in various other ways. It is used extensively in construction as a wall and facing material; chipped rock and sand from coquina are used as a filler for light concrete. In addition, coquina is used in the production of lime and other binding materials. It is extracted in quarries.

Coquina is widespread in the Neogene beds of the southern USSR: in the Moldavian SSR, in the Crimean (the Mamai, Kutur-Kaia, Bagerovo, and Karalar deposits) and Odessa oblasts of the Ukrainian SSR, in the Azerbaijan SSR (the Apsheron Peninsula), and in the Turkmen SSR. Abroad, coquina is found in Poland and Rumania.

coquina

A soft limestone formed primarily of broken shells and coral; cut into blocks and used in construction.
References in periodicals archive ?
A comparison of two Florida populations of the coquina clam, Donax variabilis Say, 1822 (Bivalvia: Donacidae) 1.
ABSTRACT Coquina clams (Donax variabilis) were sampled monthly at 2 sites in Pinellas County, Florida, to document recruitment and growth.
1992, The ecology of coquina clams Donax variabilis Say, 1822, and Donax parvula Philippi, 1849, on the east coast of Florida.
The population ecology and reproductive biology of coquina clams (Donax variabilis) on a Florida beach.
1978 A comparison of intertidal distribution, growth rates and shell polychromism between two Florida populations of the coquina clam, Donax variabilis Say, 1822 (Bivalvia: Donacidae), M.
The variable coquina clam, Donax variabilis Say, 1822, is one of the most common, recognizable bivalve mollusks from sandy beach habitats of the southeastern United States.
2004) for archaeological coquina clam shells excavated from middens in northeastern Florida.
Stable isotope evidence of middle to late Holocene seasonality and temperature change in archaeological coquina clam shells from Florida.
Florida coquina clams normally are not exploited as a food resource by humans today; however, archaeological sites in northeastern Florida attest to the fact that preColumbian people consumed vast quantities of coquina clams between the middle Archaic (ca.
Coquina clams, Donax denticulatus, called almejas (Spanish) or ahis (Miskito) locally, are numerous in the surf zone along Caribbean beaches of Honduras.