Paracale Soil Samples

Paracale, Bikol, Philippines

A while ago I acquired some soil samples from the gold mines in Paracale. The soil samples are reportedly the ones in which the tektites were found. These were not collected or witnessed by a geologist so there may be some uncertainty. It is possible that the tektite was simply placed in a soil sample, but the samples themselves do genuinely come from the Paracale region.

Tektites from Bikol are the most heavily etched in the Philippines, so it is interesting to compare them with soil samples from Belitung, Indonesia. The tektites in Belitung are also very heavily etched.

It would certainly appear that the environment is similar. In Belitung samples are quartz rich with a swelling clay matrix. The lithology is weathered from granite. In Bikol the lithologies are often very similar.

Lithology 1:

ABOVE: A 509g sphere was reportedly found in this clay.

ABOVE: A close-up when dry.

ABOVE: Add water and 3 seconds later it looks like this. This clay swells a lot - similar to the Belitung samples.

ABOVE: Within the clay many quartz grains are evident. The metal bar is 1mm in diameter.

Silty/sandy claystone: Pale yellowish orange (10 YR 8/6) when dry. Dark yellowish orange (10 YR 6/6) when wet. The claystone was hard and brittle when dry, becoming soft, but not sticky, when wet. The claystone had a high shrink-swell capacity (readily absorbing water). Quartz grains were matrix supported and ranged in size from fine to coarse sand grade (0.125mm-1.0mm). Occasionally very fine grains and silt grade material was observed. Rarely very coarse grains were noted. Quartz grains were sub-angular to sub-rounded, sub-spherical and poorly sorted.


Lithology 2:

ABOVE: A 329g grooved 'sphere'.

ABOVE: A piece of wood in the centre of the image. Not great colours I'm afraid. The rock in the bottom left of the image is the same composition as those in the gravel sample below - quartz dominated.

ABOVE: Fossil resin ('amber') found in the sample. The metal bar is 1mm in diameter.

Argillaceous Sandstone: Pale yellowish orange (10 YR 8/6) with traces of dark yellowish orange (10 YR 6/6) when dry. Dark yellowish orange (10 YR 6/6) to dark grey (N3) when wet. Hard and brittle when dry. Moderate shrink-swell capacity (readily absorbing water). This argillaceous sandstone was clast supported with 25% medium to very coarse 0.25mm to 2.0mm+) angular quartz grains. 75% of the clasts comprised lithic fragments, which were sometimes very large, and were primarily quartz in composition. A considerable quantity of wood was encountered, some of which was partially pyritised, indicative of an anoxic environment. Occasional resin (‘amber’) was also identified. This lithology was non-calcareous and non- fossiliferous (aside from the wood debris).


Lithology 3:

ABOVE: A 246g 'Hamburger'.

ABOVE: A very mixed particle size!

ABOVE: Angular quartz grains and a small gastropod.

ABOVE: A gastropod that looks marine.

ABOVE: Angular quartz grains and a small calcareous benthic foraminifera - either Elphidiella sp. or Elphidium sp. Either way a marine foraminifera.

ABOVE: Large quartz, or at least predominantly quartz, clasts in the palm of my hand.

ABOVE: A close-up of one of the quartz-dominated clasts.

Quartz sands: Very fine to coarse (0.062mm- 1mm) loose quartz sands. Greyish orange (10YR 7/4) when dry. Moderate yellowish brown (10YR 5/4) when wet. Predominantly quartz sand, very fine to coarse (0.062mm-1.0mm) sand grade, angular to sub-angular, sub-spherical to sub-elongate, very poorly sorted. The translucent quartz grains are commonly orange stained. Common macro-fossil debris up to 20mm in size, including bivalve, gastropod and coral fragments. Occasional smaller calcareous benthic foraminifera (including Elphidiella sp.). Common lithic fragments up to around 20mm diameter, predominantly quartz-based composition.


Lithology 4:

ABOVE: A 151g randomly shaped and etched tektite.

ABOVE: A close-up of some of the gravel after a very light wash. See millimeter scale at the bottom of the image.

Gravel: Pale yellowish orange (10 YR 8/6) when dry. Dark yellowish orange (10 YR 6/6) when wet. Gravel grade, unconsolidated. A variety of lithologies encountered, all of which are non-calcareous. Lithologies are predominantly quartz-based in composition. Smaller quartz grains also present. I didn't analyse the lithology of the clasts in detail, but they are all non-calcareous.


Lithology 5:

ABOVE: A 388g smooth tektite.

ABOVE: A close-up of the clay - it swells up when you add water. The metal bar is 1mm in diameter.

ABOVE: After adding water! The metal bar is 1mm in diameter.

Clay: Yellowish grey (5Y 8/1) when dry. Olive grey (5Y 4/1) when wet. Hard and brittle when dry, soft when wet. Moderate shrink-swell capacity (readily absorbing water). Quartz grains grade up to very coarse (2.0mm) in size. Moderately common organic debris (probably recent) observed. Non-calcareous.


That concludes the Paracale lithologies. I hope you enjoyed this small insight. I have given one of my suppliers a digital camera to take some shots of the mines and miners in Paracale. I've been advised not to go there myself, but I am itching to - especially when I hear reports of white guys there buying tektites!