XIX. Gemstone and Decorative Materials

Question 1

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.

Answer 1

primary deposits

Question 2

found away from where they were originally formed. They occur as alluvial or riverbed, flood plain, or beach deposits. may be in the form of narrow patches, lenses of various sizes or as evenly distributed materials in the alluvial deposits.

Answer 2

secondary deposits

Question 3

Natural gemstones may also be subdivided into two categories based on market values, namely:

Answer 3

precious and semi-precious stones

Question 4

Diamond, ruby, sapphire, and emerald

Answer 4

Precious

Question 5

“Zambales Jade“ (uvarovite), mauve, blue schist (glaucophane schist); jasper/chert; jadeite and nephrite; serpentine and spinel in—–

Answer 5

ultramafic/ophiolitic suites

Question 6

“Mindoro Jade” (sericite schists), schist, hornfels, bull quartz and gneiss in—–

Answer 6

metamorphic regions

Question 7

Jasper/chert, opal, obsidian, bloodstone and agate in—-

Answer 7

Volcanic Regions

Question 8

Garnet, feldspar, quartz, amethyst and epidote in—-

Answer 8

plutonic rocks and/or near the intrusive contacts of older formations

Question 9

Petrified wood, agate, jasper, flint clays and opal in—–

Answer 9

sedimentary rocks

Question 10

Rhodonite, pyrite, malachite, azurite, amethyst and quartz in—–

Answer 10

hydrothermal origin