**7.2.2. Other sources of phosphorus**

**Source % Source % Source %** Fluorapatite 42 Tunisia (sedimentary) 28 Basic slag 10 – 20 Kola (igneous) 40 West USA (phosphoria) 18 – 30 Bone meal 20 Nauru (phosphorite) 39 Queensland 16 – 30 Guano 12 – 15 Florida (sedimentary) 35 Venezuela 20 California (seabed) 30 Kazakhstan 23 China (Yunnan) 32 – 36 Australia (Queensland) 24 Morocco (sedimentary) 35 Kola (nepheline) 12 – 20 — —

Two important sediment relationships were developed concerning reworked phosphate in

**i.** The distribution of phosphate in surface sediments closely reflects the distribution

**ii.** The process of reworking significantly dilutes the concentration of phosphate in the

surficial sediments on the North Carolina continental shelf [26],[63]:

354 Apatites and their Synthetic Analogues - Synthesis, Structure, Properties and Applications

within underlying Miocene sediments units.

1860

and could represent important exploration tools for richer Tertiary22

within the shallow subsurface on many continental shelves in the world [26].

1880 1900 1920

Palabora, South Africa

Year of Discovery

These relationships were also recognized on the shelves of northwest and southwest Africa

22 The term Tertiary (geologic period from 66 to 2.58 ma) is no longer recognized by the International Commission on

Oulad Abdoun, Morocco

World phosphate reserves 1985

1980

phosphorites occurring

1940 1960

Onshore North Carolina, U.S.A.

Ganntour, Morocco

Offshore North Carolina, U.S.A.

Cumulative Phosphate Concentrate Resources

**Fig. 10.** The history of the discovery of the world's phosphate resources [22].

Stratigraphy.

(x1010 tonnes)

**Table 4.** Grades of apatite deposits [25].

surficial sediments.

Other important commercial sources of phosphorus (**Table 4**) include [25]:

**i. Guano** [25],[27],[64],[65],[66]: natural deposit (accumulation) formed from decay‐ ing bones and excreta from fish-eating birds.23 Fresh seafowl droppings contain about 22% N and 4% P2O5. Bat guanos are the most abundant in the cave areas of temperate and tropical regions. Although many bat guano deposits were found and mined, most of them are measured in hundreds or thousands of tons, and only sporadic production is obtained from them now. Seafowl deposits are mainly confined to islands and coastal regions at low latitudes. The largest lie along the west coasts of lower California, South America and Africa and on islands near the equatorial currents.

It was known that bird dung was utilized by the Carthaginians as early as 200 BC in order to improve crop yields. The content of P2O5 in guano can vary in dependence on the age of the deposit,24 the local climate and the bird kind. Guano deposits are found in Chile, Peru, Mexico, Seychelles, Philippines, the Arabian Gulf and else‐ where, but they account for less than 2% of the world's phosphate production.

Guano is used almost exclusively as fertilizers. The Nauru and Christmas Island phosphorite deposits may be guano in origin, but they are of very limited extent. It

<sup>23</sup> It is estimated that marine birds may take out as much as 5.1010 g of phosphorus from the ocean each year [67]. The Spanish name "guano" has an origin in Quechua word "huanu" (i.e. dung).

Guano is composed of bird droppings, and although birds existed as early as the mid-Mesozoic, their major development did not occur until the Cenozoic era, probably in the Eocene period. It follows that some seamount deposits are too old to have originated from bird droppings [64].

Most of large accumulations of guano are formed on the surface by seafowl, but smaller quantities are formed by bats and to a lesser extent by other cave-dwelling mammals and birds [27].

<sup>24</sup> Recent guano contains 10 – 12% of P2O5, but leached guano contains 20 – 32%. The mineralogy of guano is complex. Slightly decomposed deposits contain soluble ammonium and alkali oxalates, sulfates and nitrates and a variety of magnesium and ammonium-magnesium phosphates. Deeply decomposed guano consists chiefly of calcium phosphates (for example, monetite or whitlockite) [27].

is believed that rainwater can carry soluble phosphate from guano and trickle over rocks, where phosphate interacts to form phosphatic layers, e.g. phosphatized coral rock. Bird guano, mainly from Peru, achieved the greatest importance in about the middle of the 19th century, shortly before the phosphate rock industry began to establish itself.


Other important commercial sources of phosphorus are casein and lecithin. Casein is ob‐ tained from bovine milk. Lecithin was extracted from soy bean oil [25].
