Philippinite


Philippinites, or rizalites are tektites found in the Philippines. They are considered to be about 710,000 years old on the average and generally ranging in size from millimeters to centimeters. Their age corresponds with the age of other tektites in the Australian strewn tektite field. In 1964, a very large philippinite, weighing with dimensions 6.5 x 6.2 x 5.2 cm, was purchased by the University of California, Los Angeles Department of Astronomy. The heaviest philippinite ever found weighs in its splash-form, which is also the heaviest tektite of this kind.

Etymology

The term rizalite was named after the Philippine province of Rizal where the first black tektites were rediscovered in October 1926 at Novaliches. Although, it was only in 1928 that the term was proposed by American anthropologist H. Otley Beyer, dubbed as the father of Philippine tektite studies, to refer to tektites found in the Philippines. Philippinite has become the more favored term because other tektites were found in other areas of the Philippines such as the Bicol region and the town of Anda in the province of Pangasinan. Some early authors referred to Philippine tektites as "obsidianites" but that too has fallen out of use due to the introduction of the term philippinite by succeeding authors.

Uses

In ancient Philippines, tektites were used by early settlers in the Philippines as arrowheads and other tools as well as decorative purposes. During the Philippine Iron Age, due to the polish features of philippinites found in graves, it was evidenced that philippinites were used as amulets or charms. In modern times, it is generally used as a collector's item.

Composition

The following table details the chemical composition of philippinite:
OxidesContent
Number of
determinations
SiO270.66-71.644
TiO20.63-1.044
Al2O312.08-13.524
Fe2O30.59-2.033
FeO3.03-5.324
MnO0.08-0.164
CaO2.95-3.424
MgO2.23-3.654
Na2O1.21-1.664
K2O1.69-2.284
H2O+0.15-0.634
H2O−Traces1
P2O50.10-0.183