Siliceous Rocks

Siliceous Rocks

                This type of sedimentary rock is commonly formed from silica-secreting organisms such as diatoms, radiolarians, or some types of spongea. It is most commonly called diatomaceous earth. Many expert gardeners use it to aerate and balance the acidity in soil with high silica containing diatomaceous earth.

Chert

                Biologic sedimentary rocks from when large numbers of living things die, pile up, and are compressed and cemented to form rock. Accumulated and pressurized carbon-rich plant material may form coal. Deposits made mostly of animal shells may form limestone, coquina, or chert.

                Diatomite looks like chalk and fizzes easily in acid. Its made up of microscopic plankton (tiny plants) called diatoms. When the silica from diatom remains is dried and powdered, it is used as one of the main ingredients in dynamite.

                Chert (also known as flint) is very different in appearance from diatomite. Its made of hard, extremely fine, microcristalline quartz and can be dark or light in color. Chert is formed when silica in solution goes through chemical changes within limestone. It often replaces limestone and does not fizz in acid.

                Flint was used by early hunters for spear nd arrowheads. It was easily formed into points and sharp, cutting edges. Opal is a white or multicolored, less-developed crystalline form of chert used in jewelry. Opal has a high water content.

Taken from : Earth Science Demystified by Linda Williams             Written by Novita_TriswiNd

Volcanic Gases(Gas-Gas Vulkanik)

            Since the tumultuous formation of the earth, elemental gases have played a part in the composition of the planet’s makeup and matter. Volcanologists have collected gases from eruptions and lave flows at great personal risk in order to figure out their composition. Table followed lists a few gases associated with volcanic erruptions.

Volcanic Gas	Percentage of total gases (average)
Water vapor ( steam ) and carbon dioxide	90-95 %
Sulfur dioxide	< 1 %
Nitrogen	< 1 %
Hydrogen	< 1 %
Carbon monoxide	< 1 %
Sulfur	< 0.5 %
Chlorine	< 0.2 %

            The majority of gas that escapes most eruptions is made up of water vapor. Some of this water comes from ground water and sea water and some from the atmosphere. Other gases are the result of chemical changes in the magma and rock during melting and upon release to the surface. Gases that may have been trapped deep within the earth maybe coming up for the first time since the planet was formed. Can you imagine?

            Since ,most of these gases are poisonous in large quantities, many times peole are not killed by pyroclastic fallout and lave when a volcano erupts, but by the searing hot and poisonous gases that make breathing impossible. Archeologist have found that many of the people that died when Mount Vesuvius erupted werekilled by  the foul volcanic gases released during the eruption.

Translate

            Sejak huru-hara pembentukan bumi, gas-gas elemental telah memainkan perannya sebagai bagian di komposisi inti dan penyusun bumi. Para ahli vulkanologi telah menyelidiki gas-gas dari erupsi dan lelehan lava melalui resiko besar dengan tujuan menunjukkan komposisi dari gas-gas vulkanik tersebut. Tabel dibawah ini menunjukkan beberapa gas yang berhubungan dengan erupsi vulkanik.

Gas Vulkanik	Persentase Dari Total Gas (Rata-Rata)
Uap air (kukusan) dan Karbon Dioksida	90-95 %
Sulfur Dioksida	< 1 %
Nitrogen	< 1 %
Hidrogen	< 1 %
Karbonmonoksida	< 1 %
Sulfur (Belerang)	< 0.5 %
Klorin	< 0.2 %

            Mayoritas dari gas-yang muncul pada sebagian besar erupsi tersusun dari uap air. Sebagian dari air ini bersumber dari air tanah, air laut dan atmosfer. Gas lainnya merupakan hasil dari perubahan kimia di magma dan batuan selama proses pelelehan dan prosesnya menuju ke permukaan. Gas-gas tersebut mungkin terperangkap jauh di dalam bumi dan mungkin akan muncul untuk pertama kalinya ke permukaan bumi sejak bumi terbentuk. Dapatkah anda membayangkannya?

            Sejak diketahuinya sebagian besar dari gas-gas ini adalah beracun pada kuantitas yang besar, beberapa kali orang-orang tidak terbunuh oleh hujan piroklastik dan lava ketika erupsi gunung berapi, tetapi dengan gas-gas yang membakar dan beracun yang membuat bernafas menjadi mustahil. Para ahli arkeolog menemukan banyak orang yang mati ketika erupsi Gunung Vesuvius dan mereka terbunuh oleh gas vulkanik berlebihan yang muncul selama erupsi.

(Taken from : Earth Science Demystified by Linda Williams, Translated by Novita_TriswiNd)