Quartz occurs typically as fine, sand-size, clear, colorless parti- 

 cles of irregular shape with angular to subangular edges. The surface 

 of most grains is smooth and glassy without pitting or frosting. Medium 

 to coarse grains are usually more spherical in form and have rounded 

 edges. Surface pitting, frosting, and iron stains are frequently found. 



Feldspar content in the ICONS samples has not been determined; how- 

 ever, available studies of feldspar content in surficial sediments, such 

 as in the study area, indicate that it is one of the more common accesso- 

 ries of the dominant quartz-carbonate lithology. These studies provide 

 frequency data in terms of the feldspar percentage of the quartz -plus - 

 feldspar component of the fine sand or fine and medium sand-size frac- 

 tions. Cleary (1968) and Pratt (1970), who wrote specifically on the 

 Onslow and Long Bay areas, respectively, both showed feldspar content as 

 generally less than 5 percent. Field and Pilkey's (1969) study of the 

 southeastern shelf reported an average feldspar content of 2.6 percent 

 for the North Carolina shelf. Later studies of Atlantic shelf sediments 

 (Milliraan, 1972; Milliman, Pilkey, and Ross, 1972) show considerably 

 higher values for Long Bay and Onslow Bay with 5 to 10 percent for about 

 half the area and 10 to 25 percent for large segments south of Cape Look- 

 out and near Cape Fear. 



Phosphorite is distributed widely in small quantities (less than 1 

 to 3 percent) in most of the deposits sampled by the ICONS cores. It is 

 abundant only in the Miocene deposit in core 95 (Fig. 4) where it com- 

 prises almost 25 percent of the sand-size material. Phosphorite grains 

 in the study area are highly variable in character, are pale brown to 

 dark brown and black, and range from subspherical , discoidal, and pelle- 

 toid forms to irregular blocky masses; a small percentage are biomorphic 

 forms of phosphatized shells, teeth and bone fragments of marine animals 

 or casts of some animal part (Fig. 15, c). Although occasionally pitted, 

 most phosphorite particle surfaces have a smooth to highly polished 

 surface with a glossy to near virtreous surface. Most phosphorite grains 

 are opaque; however, many of the biomorphic forms and much of the mate- 

 rial in core 95 have a waxy translucent cast. 



Glauconite occurs throughout the study area but is usually in very 

 small amounts and in the fine to very fine sand-size fraction. Abundant 

 glauconite (10 to 28 percent) occurs only in cores 9, 14, and 32 where 

 it is in the fine to medium sand-size range. The glauconite grains are 

 light to dark green and usually irregular with rounded edges or with a 

 botryoidal form (Fig. 15, d). 



Colored translucent mineral grains are found in small quantities 

 most frequently in the surficial and near-surface deposits. Heavy min- 

 eral separation in bromoform (specific gravity of 2.87) of a few selected 

 samples indicates that most of the colored grains are heavier than quartz, 

 Most of the particles are pink to red, pale yellow, or pale yellowish 

 green. From mineralogical studies of the shelf surficial sediments in 

 the general region of the study area (Gorseline, 1963; Pilkey, 1963; 

 Cleary, 1968; Pratt, 1970; Milliman, Pilkey, and Ross, 1972), it seems 

 likely that most are particles of garnet, staurolite, and epidote. 



37 



