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Zambales Jade
" and its associated mauve are found in Zambales. Other occurrences are in Baler, Quezon; Balangiga, Eastern Samar; and Carascal, Surigao del Norte.
Mindoro Jade
" is associated with metamorphosed sedimentary rocks in Sta. Cruz, Occidental Mindoro.
Blue schist
was noted in the melange deposits at Hamtic, Sibalom and Belison, Antique and at San Joaquin, Iloilo.
PHOSPHATIZED GUANO
which underlies the phosphatic soil in a normal sequence of guano deposition, relates to the comparatively purer and older deposits of guano. They are porous, friable, hard, compact, and similar to the subjacent phosphatized limestone, except that they effervesce weakly or not at all in acids.
White to light gray
with white clusters giving the surface a spotty appearance. Post depositional veinlets are due to transition of opaque to translucent mineral components;
VARIOUS TYPES OF GEMSTONES AND DECORATIVE MATERIALS ACCDG. TO GEOLOGIC ENVIRONMENT AND ROCK ASSOCIATIONS IN THE COUNTRY:
"Mindoro Jade" (sericite schists), schist, hornfels, bull quartz and gneiss in metamorphic regions;
VARIOUS TYPES OF GEMSTONES AND DECORATIVE MATERIALS ACCDG. TO GEOLOGIC ENVIRONMENT AND ROCK ASSOCIATIONS IN THE COUNTRY:
"Zambales Jade" (uvarovite), mauve, blue schist (glaucophane schist); jasper/chert; jadeite and nephrite; serpentine and spinel in ultramafic/ophiolitic suites;
Pumicite
(also called volcanic ash or dust) - has the same origin, chemical composition, and glassy texture but was blown into smaller particles during the eruptive process
marble
(commercially) any crystalline rock composed predominantly of calcite, dolomite, or serpentine and takes a good polish
true marble
(in the geological sense) a metamorphic limestone or dolostone, which is thoroughly recrystallized that much or all of the sedimentary structures and biologic interlocking are obliterated.
Serpentine
, an alteration product of ultramafic rocks is found all over the ultramafic belts of the country.
Patchy light to blue gray
, conformable with highly foliated schist, with quartzite bands forming the basement rocks.
important marble deposits
. MABLE DEPOSIT IN DINGALAN BULACAN MARBLEIZED LIMESTONE
Precious Stones, Semi-precious Stones
2 CATEGORIES OF NATURAL GEMSTONES (based on market values):
LIMESTONE
A carbonate rock consisting mainly of calcite or aragonite is the mostly thoroughly exploited of all the sedimentary rocks.
PRE-CRETACEOUS, PROBABLY CARBONIFEROUS TO MIDDLE JURASSIC
Ammonite-bearing limestone bodies regionally metamorphosed to marble. These marbleized limestone deposits are closely associated with quartzite, slate, phyllite, and mica-schists, considered part of the basement complex.
carbon, hydrogen, and oxygen
Among the sixteen chemical elements essential for plant growth, _________________ are needed in large amounts (produced by water and air)
CLASIFICATION OF GEMSTONE AND DECORATIVE MATERIALS
Based on origin, formation and deposition, gemstone deposits in the country are classified into primary and secondary
residual, fluvial, marine and lacustrine.
CLASSIFICATION Sand and gravel deposits, on the basis of origin,
CLASSIFICATION OF MAGNESITE
CLUSTERED NODULES OR CONCRETIONS MASSIVE DEPOSIT FOLDED SHEETS FILLING THE FRACTURES
basalt and diabase
Commercially, these rocks are called trap or trap rocks. Basalt and diabase are essentially used as crushed stones, which are utilized for concrete aggregates and rock ballast, roofing granules and riprap
Bardillo
Dark bluish gray to blackish with white patches and veinlets, known as
3 CLASSES OF GUANO
FRESH GUANO PHOSPHATIC SOIL PHOSPHATIZED GUANO
CLASSIFICATION OF PHOSPHATE ROCKS
GUANO-DERIVED PHOSPHATE ROCK DEPOSIT OPEN-CUT PHOSPHATE DEPOSITS
VARIOUS TYPES OF GEMSTONES AND DECORATIVE MATERIALS ACCDG. TO GEOLOGIC ENVIRONMENT AND ROCK ASSOCIATIONS IN THE COUNTRY:
Garnet, feldspar, quartz, amethyst and epidote in plutonic rocks and/or near the intrusive contacts of older formations;
CLASSIFICATION OF LIMESTONES
HIGH-CALCIUM LIME MAGNESIAN LIME OYSTER-SHELL LIME HYDRATED LIME
JASPER
JASPER is red to reddish brown, with gray variegated designs. Other varieties show alteration of reddish brown and colorless bands. These are opaque, granular to cryptocrystalline, hard, dense, brittle and dull, with conchoidal fracture. The hardness is 7.0 in Moh's scale; the specific gravity, 2.6 to 2.9. The jasper is polycrystalline quartz in a microcrystalline quartz matrix.
VARIOUS TYPES OF GEMSTONES AND DECORATIVE MATERIALS ACCDG. TO GEOLOGIC ENVIRONMENT AND ROCK ASSOCIATIONS IN THE COUNTRY:
Jasper/chert, opal, obsidian, bloodstone and agate in volcanic regions;
Pentellic;
Light bluish gray with whitish spots, generally coarse-grained, locally known romblon
caustic-calcined magnesia
Magnesium is an essential element in plant and animal metabolism, and is added to fertilizers in the form of .
marble varieties in Bulacan, the following are notable.
Mariposa A, Mariposa B , Bigti capistrano, Sierra madre,
Mindoro Jade
Mindoro Jade" is associated with a series of parallel quartz veins within the limestone member of the Mansalay Formation. These veins average 1 m wide, 20 m high and traceable for 25 m along northwest strike.
FERTILIZER MINERALS
Minerals that are utilized as fertilizer materials are guano, phosphate rock, limestone, dolomite, magnesite, peat, pyrite and sulfur.
tektites,(2) pearls,(3) corals,(4) amber,(5) poka shells, (6)jet (coal fragment
OTHER TYPES OF GEMSTONE AND DECORATIVE MATERIALS
3.575 billion cu. m
PH's total reserve of marbleized limestone: reaches to
10.898 billion cu. m
PH's total reserve of metamorphic/true marble: reaches to
6 MAJOR GROUPS OF LIMESTONE DEPOSITS
PRE-CRETACEOUS, PROBABLY CARBONIFEROUS TO MIDDLE JURASSIC CRETACEOUS LIMESTONE DEPOSITS PALEOCENE TO OLIGOCENE TRANSGRESSIVE REEF LIMESTONE LATE OLIGOCENE TO MIDDLE MIOCENE TRANSGRESSIVE REEF LIMESTONE UPPER MIOCENE LIMESTONE PLIOCENE TO PLEISTOCENE REEF LIMESTONE
VARIOUS TYPES OF GEMSTONES AND DECORATIVE MATERIALS ACCDG. TO GEOLOGIC ENVIRONMENT AND ROCK ASSOCIATIONS IN THE COUNTRY:
Petrified wood, agate, jasper, flint clays and opal in sedimentary rocks
ROMBLON
Production of marble within the Romblon Group of Islands, regarded as the classic quarrying area in the country, has been going on since the start of this century with brief interruptions. Tablas Island, the largest, has fossiliferous limestone of Miocene to Pliocene age. This marble reserve is placed at 148.721 million metric tons.
VARIOUS TYPES OF GEMSTONES AND DECORATIVE MATERIALS ACCDG. TO GEOLOGIC ENVIRONMENT AND ROCK ASSOCIATIONS IN THE COUNTRY:
Rhodonite, pyrite, malachite, azurite, amethyst and quartz in deposits of hydrothermal origin
classification
The local adobe may be classified as to its color. Principally, it may be classified as gray-white, brown, red and black adobe. Gradation from one shade of color to the other, with minor differences in texture is common
marble
The marble deposits are the portions of the Eocene and Miocene limestone members.
PYRITE AND SULFUR
The principal sources of sulfur in the Philippines are the pyrite concentrate recovered as by-product from various copper mines and the natural sulfur deposits. Elemental sulfur deposits in the vicinity of active and dormant volcanoes, such as Mount Pinatubo and Mount Halcon, could be major sources in the future.
dolomitization
The transformation of normal limestone to dolomitic limestone or dolomite is known as .
FERTILIZER MINERALS
These materials serve either as natural raw fertilizers and soil conditioners, as essential fertilizer raw materials or as ingredients in the manufacture of inorganic and chemical fertilizers.
571,230 MT
Total reserve of phosphate rock deposits in the country reaches to _____ with P2O5 content averaging 24 percent
VOLCANIC TUFF
Tuff deposits, which exhibit considerable variation in texture and color, are products of Quaternary explosive volcanism.
Golden Romblon;
Whitish to cream color, rusty yellow veined and spotted, locally known as
SAND AND GRAVEL
With the growth of infrastructure programs like the construction of circumferential highways, roads, buildings and other related projects,______________, the basic raw materials for construction, are greatly in demand.
Zambales Jade
Zambales Jade occurs as cobbles and boulders on top of ridges and valley slopes. It contains sharply crystallized dodecahedral crystals of garnet, uvarovite, xenoblastic feldspar, minor diopside and sphene that lie in a granoblastic mosaic of quartz and plagioclase. This hornfelsic rock Is composed of 67% feldspar (potash and plagioclase), 18% quartz, 10% garnet; 4% sphene, and 3% diopside.
DOLOMITE
a carbonate of calcium and magnesium, is ideally composed of 21.70% magnesia, 30.40% lime and 47.90% carbon dioxide.
Pumice
a cellular, glassy rock formed by explosive volcanism
MAGNESITE
a natural form of magnesium carbonate with ideal magnesia content of 47.60 % is an important source of magnesium for fertilizer.
properties of the aggregate
affect concrete characteristics such as density, strength, durability, thermal conductivity, shrinkage and creep. The shape and textures of the aggregate particles and their grading (distribution of particle sizes) are important factors influencing the workability and strength of concrete.
Tanay gray
appears fine-grained, dark to medium gray, shaded ground, and decorated with sutured network of fine veinlets. Recently, white-veined, brecciated, red-colored marble is quarried south of barangay Sto. Niño from a number of reef-like features.
Hornfels, quartz, schist and gneiss
are also common in various metamorphic regions.
Flint clays
are associated with tuffaceous sediments in Capalonga, Camarines Norte.
most common rocks utilized in the processing of rock aggregates
are basalt, andesite and metavolcanic rocks, which are widely distributed in the Philippines.
basalt and diabase
are dark, fine-grained igneous rocks composed essentially of plagioclase feldspar and ferromagnesian minerals, particularly augite. Accessories include magnesite, apatite and olivine.
SECONDARY DEPOSITS
are found away from where they were originally formed. They occur as alluvial or riverbed, flood plain, or beach deposits. Secondary deposits may be in the form of narrow patches, lenses of various sizes or as evenly distributed materials in the alluvial deposits.
Tektite deposits
are found in Novaliches, Quezon City; Bolinao and Anda, Pangasinan; Ilagan, Isabela; and Paracale, Camarines Norte.
PRIMARY DEPOSITS
are found in places where they were originally formed (in situ), together with the associated rocks. They occur as dissemination, veins, dikes, lenses or beds within various rock types.
basalt and diabase
are hard stones; although quartz is a minor constituent it is not as abrasive to machinery as granite and sandstone. It is somewhat heavier than most other varieties of crushed stones, thus making it more valuable than other varieties of crushed stones.
Well-developed crystals of sphalerite and galena
are in San Mauricio Mine, Jose Panganiban, Camarines Norte and Kawit, Ayala, Zamboanga City.
ROCK AGGREGATES
are produced by crushing, screening and washing of andesite, basalt, limestone, marble, metavolcanic and other rock materials which meet certain requirements as to strength, soundness, and other specifications utilized in much the same way as sand and gravel.
Rock aggregates
are produced by crushing, screening and washing of andesite, basalt, limestone, marble, metavolcanic and other rock materials which meet certain requirements as to strength, soundness, and other specifications utilized in much the same way as sand and gravel.
Fluvial deposits
are sand and gravel, picked-up, transported and deposited by stream action. Coarse sand may be interspersed with lenses of fine sand and clay. Deposits have their long axes parallel to the direction of the stream flow. The beds usually vary greatly in thickness and may be complex in composition.
Jasper and/or chert
associated with basalt of the ophiolites were identified in Dasol and Mabini, Pangasinan; Belison and Sibalom, Antique; and Tandag, Lanuza and Madrid, Surigao del Sur.
LATE OLIGOCENE TO MIDDLE MIOCENE TRANSGRESSIVE REEF LIMESTONE
associated with marine shelf sediments largely wackes and shales, underlain by conglomerates or associated with paralic coal measures and averaging nearly 500 m thick are disposed along the eastern fringe of the Philippine Archipelago
Agate, jasper and opal
associated with the clastic member of the Angat Formation were noted in San Miguel and Doña Remedios Trinidad, Bulacan; within the graywacke and limestone area in Pasacao, Camarines Sur; and in carbonaceous silt and limestone in Claveria and Uson, Masbate.
PALEOCENE TO OLIGOCENE TRANSGRESSIVE REEF LIMESTONE
associated with thick shelf and deep marine water deposits largely wackes and shales (flysch sediments), with minor conglomerated, basalt, dacitic and andesitic flows, and pyroclastics.
Spinel disseminations
associated with ultramafic rocks are in Canimog Island, Mercedes, Camarines Norte.
Bloodstone
associated with volcanic rocks was noted in Maangas Presentacion, Camarines Sur.
Residual deposits
commonly form rock mantle over the parent formation and are formed by the mantle weathering in place of the parent rock or superimposed formations. Ordinarily, they are intermixed with clay and inferior particles that lessen their commercial importance.
Marine and lake deposits
consist of well-sorted materials with segregated coarse and fine particles. Their long axis is usually parallel to the shoreline. Marine sand ranges from angular to well rounded; pebbles are usually well rounded. Normally, marine sand and gravel deposits consist of hard, tough materials coming from streams and reworked by wave, tidal and marine current action.
Tagabenit
consisting of fossils, with obliterated outlines embedded in fine-grained, cloudy calcitic mass. Few thin veinlets interlace with thicker though irregular calcite veins filled with clear, medium-grained calcspar. Texture is dominated by patchy gray with groundmass of comminuted pepper and salt appearance. Newly generated calcite veinlets are intersecting at acute angles.
FOLDED SHEETS FILLING THE FRACTURES
constitute the third type. The crest of the fold lies on the plane of the fractures and is mostly in contact with the wallrock.
LOCAL GUANO
deposits are confined to limestone caves and caverns which are the natural habitat or breeding ground of birds (swallows) and bats.
dolomitization
favorably takes place when the calcium carbonate is aragonite. Aragonite is the dominant component of coralline limestone and since the Carcar Formation is undoubtedly coralline, it is therefore favorable for such dolomitization process
GUANO-DERIVED PHOSPHATE ROCK DEPOSIT
found singly or in combination with guano - The leaching of the more soluble phosphates in guano and subsequent deposition in and/or replacement of the underlying limestone bedrock produce the guano-derived rock phosphates.
garnet
garnet is usually dark green with shades of pink, brown and violet (mauve). Its hardness ranges from 5.5 to 6.5 in Moh's scale while the specific gravity varies from 2.3 to 2.7. Under the microscope, it exhibits a zoned, feebly birefringent character. X-ray analyses show that the composition of the garnet lies within the range of the uvarovitegrossularite- andradite series.
commercial trade names
give the quarry location, color, texture, and a descriptive word for the pattern and texture of the polished marble product.
NATURAL RAW FERTILIZERS
in a crudely ground or powdered state, they are added to correct nutrient deficiencies and to neutralize unwanted acidity or extreme alkalinity in certain types of soils.
Rock asphalt
in the Philippines are bitumen impregnations during the MiocenePliocene epoch in shale and sandstone in some parts of the islands including Villaba, Leyte. It is used as binder in road pavement.
PYRITE (FeS2)
is a common mineral associated with copper, lead, zinc, gold and other metallic minerals. Economic concentrations of pyrite occur with disseminated and massive sulfide types of copper deposits. Typical are the Toledo Mine in Cebu; Thanksgiving Mine in Benguet; and Bagacay Mine in Samar.
Villaba rock asphalt
is a lenticular body in a shale-sandstone series. The body is composed of interbedded, medium to coarse-grained sandstone with layers that show abundant fragments of limestone impregnated with tar and bitumen.
Bulacan beige
is a light pink, fine-grained, with varied light pink to pinkish red bands and creamy blotch due to numerous white calcitic fossils. It is strongly stylolitic and with fairly open sutures.
Palawan black
is almost black in color; with fine, crystalline mosaic of cloudy calcite containing obliterated organic remains. Sometimes, opaque dusts are concentrated along grain boundaries. Texture is characterized by indistinct black with dark gray dots of fossils irregularly distributed in the groundmass.
Obsidian
is associated with Quaternary volcanics in Mabitac and Nagcarlan, Laguna and in Pagudpud, Ilocos Norte.
Southern cloud-light
is brown buff in color, fine-grained, with nodular pattern formed by dark sutures subdividing the surface into crenellated nodules of gray to dark buff color.
Tanay tea
is brown gray in color, fine grained, with lighter shades of nodular gray patches, with white, translucent to opaque calcite veinlets forming network of yellow golden sutures.
Bigti capistrano
is creamy to medium buff, with fossil content about 50% of the mass,and mainly of large forams and algae. Matrix is microcrystalline mosaic of turbid calcite, with few veinlets cutting across the fossils. On polished slab, it appears strongly stylolitic, with medium buff groundmass and lighter patches.
OYSTER-SHELL LIME
is crushed oyster shell that has been calcined and used as agricultural lime or simply aglime.
PEAT
is dark brown to black carbonaceous residuum produced by the partial decomposition and disintegration of mosses, sedges, trees, and other plants that have grown or accumulated in shallow lakes, marshes, and tidal flats.used as soil conditioner and as ingredient or filler in mixed fertilizer.
Sierra madre
is dark buff in color, with dark buff ground comminuted with fragments of fossils and algae, with light to dark discontinuous calcitic veinlets.
Mariposa B
is dark buff to light brown in color, with lenticular gray blotches in the direction of streaks giving grained texture, with thin, discontinuous calcite veinlets at right angles with streaks. It is strongly fossiliferous and takes a medium polish.
Star southern cloud-medium
is dark buff, fine-grained, with lighter creamcolored stringers enclosing orbicular fossils and blebs. Occasionally these are articulated with dark stringers and white calcite veinlets.
Southern cloud-dark
is dull brownish buff, with gray to buff varied and shaded ground subdivided into nodules by dark patches with stringers. Calcitic fossil blebs and blotches render the polished slab a cloudy look
OPEN-CUT PHOSPHATE DEPOSITS
is exemplified by phosphorite associated with massive to poorly bedded, porous, coralline, and frequently fractured limestone formations of Pliocene to Pleistocene age.
Palawan gray
is fine-grained, with calcitic groundmass containing abundant fossils of large and small forams and minor algae. On polished slab, it is dark gray in color, with streaks of darker gray in between stylolitic markings. Fine black specks are fairly distributed forming wiplike streaks, with white calcite veinlets and vug fillings.
HYDRATED LIME
is hydrated calcium oxide, Ca(OH)2, with 24 percent water.
HIGH-CALCIUM LIME
is made from burning limestone with 50-55% calcium oxide and 40-55% carbonic acid, containing small percentages of magnesia, silica, iron and alumina. A lime derived from these raw materials yields 90-98% calcium oxide.
Mariposa A
is medium cream pink in color, fine-grained, with varied cream pink to pinkish buff streaks giving curved lamination effect. White to off-white fossil blebs and fragments are crowding some of the streaks.
Cabayugan
is medium gray in color, with dark irregularly recrystallized and finegrained matrix containing obscured fossils. On polished surface, it is of fawn-gray ground, with large medium gray patches fanning out into thin, curved to straight filaments forming a renticular pattern.
Gumamela
is pink in color, with breccia in dark brown to red matrix. It has angular to sub angular elements with dark red, well defined blebs, large, irregularly shaped algal detritus, which are partly recrystallized set in fine-grained and poorly recrystallized calcite matrix.
Tanay black
is strongly fossiliferous, with small elongated dots in all sizes and shapes in dull black matrix. The gray marble is fine grained, with numerous white calcitic and yellow to red limonitic veinlets. It is highly fossiliferous, with prominently coralline and foraminiferal portions.
peat
is used as fuel and raw material for producing mountain wax, peat coke or char, gas, and tar products.
Concrete
is usually made from a mixture of water, cement, and both coarse and fine aggregate. The water and the cement form the paste, whilst the aggregate forms inert filler.
Tanay red
is yellow-red on polished slab, fine grained, with salmon pink ground, varied patches of creamy pink to dark red, with white calcite veinlets and are strongly fossiliferous. Limonite micro stylolites cut across, displaying their contiguous parts.
jade
jade is generally greenish gray to light green, with hardness of 3.5 to 4.0 in the Moh's scale, and shows a vitreous to silky or pearly luster. With fibroblastic texture, it consists of tabular plates of muscovite and scaly aggregates of sericite, with accessory highly corroded apatite. It is composed of 40% muscovite, 50% sericite, 5% apatite and traces of quartz, calcite and chlorite. The gemstone is petrologically termed green mica schist due to the presence of abundant sericite.
UPPER MIOCENE LIMESTONE
largely calcarenite or silty limestone associated with marine sediments and volcanics. Predominantly composed of sandstone, siltsone, marl and limestone, the sediments of Late Miocene age vary from several hundred to 1,500 m and average from 500-800m. Thick.
PLIOCENE TO PLEISTOCENE REEF LIMESTONE
largely coralline and associated with marine and terrestrial sediments (molasses), water laid pyroclastic, and localized terrace gravel deposits ranging from 150-400 m. thick. These limestone bodies are associated with flat to very gently folded, fine to medium-grained sediments with abundant mollusks and small foraminiferas.
PUMICE AND PUMICITE
light colored volcanic glasses, produced during the Pliocene and Quaternary volcanism
PHOSPHATE ROCK
made up primarily of chloride, fluoride, carbonate, or hydroxyl forms of apatite, is the main source of phosphate in chemical fertilizers.
PUMICE AND PUMICITE
many uses of pumice and related volcanic materials (pumicite, scoria and cinder) - due to their properties of abrasiveness, inertness and lightness. utilized therefore as lightweight aggregates, additives for pozzolan cement, abrasives, soil conditioners, carriers for insecticides, filters, extenders and insulation materials.
Tanay red
marble variety belongs to the biohermal phase of the Angat Formation and dated late early Miocene.
structural and building materials
marble, pumice/pumicite, rock aggregates, rock asphalt, sand and gravel, and volcanic tuff.
obsidian
obsidian was formerly used as aggregates and decorations on concrete walls of houses. It is a dark colored volcanic glass with round or elongated bubbles, amygdules, and pitted surface. It occurs as cobbles and boulders scattered along the lower ridges of volcanic center. On fresh fracture, the surface is conchoidal; luster is vitreous. It is opaque to transparent. The hardness ranges from 5 to 5.5 in Moh's scale; specific gravity, from 2.33 to 2.50 depending on the abundance of vesicles. It consists mainly of glass with some minute inclusions of crystallites and amygdules of quartz and zeolite.
MASSIVE DEPOSIT
occupying the full width of the fracture belongs to the second type. The magnesite occupies the spaces in the brecciated zones of peridotite without showing any folding.
Pearls, coral, and shells
occur in marine environment while amber is known in some forested areas. Our pearl culture is in Samal Island, Davao.
The jasper/chert deposits of Pagudpud and Espiritu, Ilocos Norte and in Milagros and Uson, Masbate
occur in volcanic and pyroclastic rocks consisting of andesite, basalt and tuffs.
CRETACEOUS LIMESTONE DEPOSITS
occurring as lenticular bodies, are in close association with pelagic to semi-pelagic sediments, turbidites, cherts, and spilites. Most notable are the fragmentary Orbitolina-bearing limestones associated with the metamorphics.
Garnet crystals
occurring in muscovite and biotite schist were observed in Tunaw Island, Jose Panganiban, Camarines Norte.
Petrified wood
occurs in the sandstone and shale in Ilagan, Isabela; in the tuffaceous shale of Labo, Camarines Norte; and in the tuffaceous sandstone and shale in Morong, Rizal
CLUSTERED NODULES OR CONCRETIONS
on both walls of the fracture constitute the first type. Coalesced nodules exhibit deformed ovoid and spherical shapes
PHOSPHATIC SOIL
produced by the mixing of transported soil material with droppings and remains of bats and birds deposited inside the cave, is relatively loose and much lighter in color than fresh guano
Chalcopyrite and secondary minerals
such as malachite, azurite and chrysocolla are in several copper deposit areas.
fossiliferous marble
synonymous with marbleized limestone, although this is not considered true marble by petrologists, particularly if the sedimentary and biologic textures are still well preserved
tektite
tektite deposit known to the local inhabitants as bisnu, is in Malaguit River at Paracale, Camarines Norte. Tektites are found in riverbeds and alluvial plains as pebbles and cobbles of various shapes and colors- black, brown and olive green. They are small, rounded, pitted bodies of silicate glass with vitreous luster and conchoidal fracture. The hardness is 5.5 in Moh's scale; specific gravity, from 2.34 to 2.51.
GUANO
the accumulated excrement and remains of birds and bats, provide the most important organic source of phosphorus and nitrogen.
volcanic rocks
underlie opal and agate deposits of Pa-ayas, Burgos, Ilocos Norte and Villacorta, Pangasinan.
MAGNESIAN LIME
used in agriculture contains 5 to 20 percent magnesia and 70 to 85 percent calcium oxide. A bushel of magnesian lime weighs about 70 pounds; a highcalcium lime, 90 to 95 pounds.
FRESH GUANO
usually dark chocolate brown, soft, oblong, and about the size of a grain of palay which eventually disintegrates into pulverulent masses.
Rhodonite veins
were noted in Acupan Mines, Benguet; Sagada and Lubuagan, Mountain Province; and in Vulcan Mines, Cordon, Isabela.
Minor floats of jadeite and nephrite
were observed in Belison and Sibalom, Antique but the main source has not been identified