MICA

The mica group of sheet silicate
( phyllosilicate ) minerals includes several
closely related materials having close to
perfect basal cleavage . All are monoclinic, with
a tendency towards pseudohexagonal crystals ,
and are similar in chemical composition. The
nearly perfect cleavage, which is the most
prominent characteristic of mica, is explained
by the hexagonal sheet-like arrangement of its
atoms.
The word "mica" is derived from the Latin
word mica , meaning "a crumb", and probably
influenced by micare , to glitter. [1]
Classification
Chemically, micas can be given the general
formula [2]
X2 Y 4–6 Z 8O 20 ( OH, F) 4
in which X is K , Na, or Ca or less
commonly Ba , Rb, or Cs ;
Y is Al , Mg , or Fe or less commonly Mn , Cr ,
Ti , Li, etc.;
Z is chiefly Si or Al, but also may include
Fe 3+ or Ti.
Structurally, micas can be classed as
dioctahedral ( Y = 4) and trioctahedral ( Y = 6).
If the X ion is K or Na, the mica is a
"common" mica, whereas if the X ion is Ca,
the mica is classed as a "brittle" mica.
Trioctahedral micas
Common micas:
Biotite
Lepidolite
Muscovite
Phlogopite
Zinnwaldite
Brittle micas:
Clintonite
Interlayer deficient micas
Very fine-grained micas, which typically show
more variation in ion and water content, are
informally termed "clay micas". They include
Hydro-muscovite with H3 O + along with K in
the X site;
Illite with a K deficiency in the X site and
correspondingly more Si in the Z site;
Phengite with Mg or Fe 2+ substituting for Al
in the Y site and a corresponding increase in Si
in the Z site.
Occurrence and production
Mica embedded in metamorphic rock.
Mica is widely distributed and occurs in
igneous , metamorphic and sedimentary
regimes. Large crystals of mica used for
various applications are typically mined from
granitic pegmatites.
Until the 19th century, large crystals of mica
were quite rare and expensive as a result of
the limited supply in Europe. However, their
price dramatically dropped when large reserves
were found and mined in Africa and South
America during the early 19th century. The
largest documented single crystal of mica
( phlogopite ) was found in Lacey mine, Ontario,
Canada ; it measured 10×4.3×4.3 m and
weighed about 330 tonnes .[3] Similar-sized
crystals were also found in Karelia , Russia .[4]
The British Geological Survey reported that as
of 2005, Koderma district in Jharkhand state in
India had the largest deposits of mica in the
world. China was the top producer of mica
with almost a third of the global share, closely
followed by the US, South Korea and Canada.
Large deposits of sheet mica were mined in
New England from the 19th century to the
1970s. Large mines existed in Connecticut ,
New Hampshire, and Maine.
Scrap and flake mica is produced all over the
world. In 2010, the major producers were
Russia (100,000 tonnes), Finland (68,000 t),
United States (53,000 t), South Korea (50,000
t), France (20,000 t) and Canada (15,000 t).
The total production was 350,000 t, although
no reliable data were available for China. Most
sheet mica was produced in India (3,500 t)
and Russia (1,500 t). [5] Flake mica comes
from several sources: the metamorphic rock
called schist as a byproduct of processing
feldspar and kaolin resources, from placer
deposits, and from pegmatites. Sheet mica is
considerably less abundant than flake and
scrap mica, and is occasionally recovered from
mining scrap and flake mica. The most
important sources of sheet mica are pegmatite
deposits. Sheet mica prices vary with grade
and can range from less than $1 per kilogram
for low-quality mica to more than $2,000 per
kilogram for the highest quality. [6]
Properties and uses
The mica group represents 37 phyllosilicate
minerals that have a layered or platy texture.
The commercially important micas are
muscovite and phlogopite, which are used in a
variety of applications. Mica’s value is based
on several of its unique physical properties.
The crystalline structure of mica forms layers
that can be split or delaminated into thin
sheets usually causing foliation in rocks. These
sheets are chemically inert, dielectric, elastic,
flexible, hydrophilic, insulating, lightweight,
platy, reflective, refractive, resilient, and range
in opacity from transparent to opaque. Mica is
stable when exposed to electricity, light,
moisture, and extreme temperatures. It has
superior electrical properties as an insulator
and as a dielectric, and can support an
electrostatic field while dissipating minimal
energy in the form of heat; it can be split very
thin (0.025 to 0.125 millimeters or thinner)
while maintaining its electrical properties, has
a high dielectric breakdown, is thermally stable
to 500 °C, and is resistant to corona
discharge . Muscovite, the principal mica used
by the electrical industry, is used in capacitors
that are ideal for high frequency and radio
frequency. Phlogopite mica remains stable at
higher temperatures (to 900 °C) and is used in
applications in which a combination of high-
heat stability and electrical properties is
required. Muscovite and phlogopite are used in
sheet and ground forms. [7]
Ground mica
The leading use of dry-ground mica in the US
is in joint compound for filling and finishing
seams and blemishes in gypsum wallboard
( drywall). The mica acts as a filler and
extender, provides a smooth consistency,
improves the workability of the compound, and
provides resistance to cracking. In 2008, joint
compound accounted for 54% of dry-ground
mica consumption. In the paint industry,
ground mica is used as a pigment extender
that also facilitates suspension, reduces
chalking, prevents shrinking and shearing of
the paint film, increases resistance of the paint
film to water penetration and weathering, and
brightens the tone of colored pigments. Mica
also promotes paint adhesion in aqueous and
oleoresinous formulations. Consumption of
dry-ground mica in paint, the second ranked
use, accounted for 22% of the dry-ground mica
used in 2008. [6]
Ground mica is used in the well-drilling
industry as an additive to drilling fluids. The
coarsely ground mica flakes help prevent the
loss of circulation by sealing porous sections
of the drill hole. Well drilling muds accounted
for 15% of dry-ground mica use in 2008. The
plastics industry used dry-ground mica as an
extender and filler, especially in parts for
automobiles as lightweight insulation to
suppress sound and vibration. Mica is used in
plastic automobile fascia and fenders as a
reinforcing material, providing improved
mechanical properties and increased
dimensional stability, stiffness, and strength.
Mica-reinforced plastics also have high-heat
dimensional stability, reduced warpage, and
the best surface properties of any filled plastic
composite. In 2008, consumption of dry-
ground mica in plastic applications accounted
for 2% of the market. The rubber industry used
ground mica as an inert filler and mold release
compound in the manufacture of molded
rubber products, such as tires and roofing. The
platy texture acts as an antiblocking,
antisticking agent. Rubber mold lubricant
accounted for 1.5% of the dry-ground mica
used in 2008. As a rubber additive, mica
reduces gas permeation and improves
resiliency. [6]

Indian Dresses


Clothing in India varies from region to region depending on the ethnicity, geography, climate and cultural traditions of the people of that region. Historically, men and women clothing has evolved from simple Langotas, and loincloths to cover the body to elaborate costumes not only used in daily wear but also on festive occasions as well as rituals and dance performances. In urban areas, western clothing is common and uniformly worn by people of all strata. India also has a great diversity in terms of weaves, fibers, colours and material of clothing. Colour codes are followed in clothing based on the religion and ritual concerned. For instance, Hindu ladies wear white clothes to indicate mourning, while Parsis and Christians wear white to weddings.

History

The Didarganj Yakshi depicting the dhoti wrap
India's recorded history of clothing goes back to the 5th millennium BC in the Indus Valley civilization where cotton was spun, woven and dyed. Bone needles and wooden spindles have been unearthed in excavations at the site.[1] The cotton industry in ancient India was well developed, and several of the methods survive until today. Herodotus, an ancient Greek historian described Indian cotton as "a wool exceeding in beauty and goodness that of sheep".[2] Indian cotton clothing was well adapted to the dry, hot summers of the subcontinent. The grand epic Mahabharata, estimated to be written between 3000-4000 BC, has a mention of an uneding saree gifted to Draupadi to protect her dignity.[3] Most of the present knowledge of ancient Indian clothing comes from rock sculptures and paintings in cave monuments such as Ellora. These images show dancers and goddesses wearing what appears to be a dhoti wrap, a predecessor to the modern sari.The upper castes dressed themselves in fine muslin and wore gold ornaments[4] The Indus civilisation also knew the process of silk production. Recent analysis of Harappan silk fibres in beads have shown that silk was made by the process of reeling, a process known only to China until the early centuries AD.[5]

According to the Greek historian Arrian:[6]


The Buddha, in Greco-Buddhist style, 1st–2nd century CE, Gandhara(Modern eastern Afghanistan).
"The Indians use linen clothing, as says Nearchus, made from the flax taken from the trees, about which I have already spoken. And this flax is either whiter in colour than any other flax, or the people being black make the flax appear whiter. They have a linen frock reaching down halfway between the knee and the ankle, and a garment which is partly thrown round the shoulders and partly rolled round the head. The Indians who are very well-off wear earrings of ivory; for they do not all wear them. Nearchus says that the Indians dye their beards various colours; some that they may appear white as the whitest, others dark blue; others have them red, others purple, and others green. Those who are of any rank have umbrellas held over them in the summer. They wear shoes of white leather, elaborately worked, and the soles of their shoes are many-coloured and raised high, in order that they may appear taller."

 10 Fun Facts 


1. Cockroaches can lives for 9 days after their head been cut off. 
2. Dolphins sleep with one the eye open. 
3. Earthworms are known as nature's ploughmen.
4. The moon is nearly 3,85,000 km away from the earth. 
5. Polar bear has black skin. 6. The biggest leaves is water platter. 
7. 3000 trees are found in rain forest. 
8. 6 times a big cat can see better than human being. 
9. The volume of the earth's moon is the same as the volume of the Pacific ocean. 
10. The smallest cell is PPLO ( pleuro pneumonic like organism.

Rafflesia

Rafflesia is a genus of parasiticflowering plants. It contains approximately 28 species (including four incompletely characterized species as recognized by Willem Meijer in 1997), all found in southeastern Asia, onIndonesia, Malaysia, Borneo, Sumatra,Thailand and the Philippines.[1]

Rafflesia was found in the Indonesianrain forest by an Indonesian guide working for Dr. Joseph Arnold in 1818, and named after Sir Thomas Stamford Raffles, the leader of the expedition. It was discovered even earlier by Louis Deschamps in Java between 1791 and 1794, but his notes and illustrations, seized by the British in 1803, were not available to western science until 1861.[citation needed]

The plant has no stems, leaves or true roots. It is a holoparasite of vines in the genus Tetrastigma (Vitaceae), spreading its absorptive organ, thehaustorium, inside the tissue of the vine. The only part of the plant that can be seen outside the host vine is the five-petaled flower. In some species, such as Rafflesia arnoldii, the flower may be over 100 centimetres (39 in) in diameter, and weigh up to 10 kilograms (22 lb). Even the smallest species, R. baletei, has 12 cm diameter flowers. The flowers look and smell like rottingflesh, hence its local names which translate to "corpse flower" or "meat flower" (see below). The foul odor attracts insects such as flies, which transport pollen from male to female flowers. Most species have separate male and female flowers, but a few have hermaphroditic flowers. Little is known about seed dispersal. However, tree shrews and other forest mammals eat the fruits and disperse the seeds.Rafflesia is the official state flower ofIndonesia, the Sabah state in Malaysia, and of the Surat Thani Province,Thailand.

The name "corpse flower" applied toRafflesia can be confusing because this common name also refers to the titan arum (Amorphophallus titanum) of the family Araceae. Moreover, becauseAmorphophallus has the world's largest unbranched inflorescence, it is sometimes mistakenly credited as having the world's largest flower. BothRafflesia and Amorphophallus are flowering plants, but they are only distantly related. Rafflesia arnoldii has the largest "single" flower of any flowering plant, at least in terms of weight. A. titanum has the largest "unbranched" inflorescence, while the talipot palm (Corypha umbraculifera) forms the largest "branched" inflorescence, containing thousands of flowers; the talipot is monocarpic, meaning the individual plants die after flowering.

Worms



The term  /ˈwɜrm/ is used in everyday language to describe many different distantly related animals that typically have a long cylindrical tube-like body and no legs. Worms vary in size from microscopic to over 1 metre (3.3 ft) in length for marine polychaete worms (bristle worms),[1] 6.7 metres (22 ft) for the African giant earthworm,Microchaetus,[2] and 55 metres (180 ft) for the marine nemertean worm (bootlace worm), Lineus longissimus.[3]Various types of worm occupy a small variety of parasitic niches, living inside the bodies of other animals. Free-living worm species may live on land, in marine or freshwater environments, or burrow.

In biology, "worm" refers to an obsoletetaxon (vermes) used by Carolus Linnaeus and Jean-Baptiste Lamarckfor all non-arthropod invertebrate, and stems from the Old Englishword wyrm. Most animals called "worms" are invertebrates, but the term is also used for the amphibian and the slow worm Anguis, a legless burrowing lizard. Invertebrate animals commonly called "worms" include annelids (earthworms),nematodes (roundworms),platyhelminthes (flatworms), marinepolychaete worms (bristle worms), marine nemertean worms ("bootlace worms"), marine Chaetognatha (arrow worms), priapulid worms, and insect such as caterpillars, grubs, andmaggots.

Historical English-speaking cultures have used the (now deprecated) termsworm, Wurm, or wyrm to describecarnivorous reptiles ("serpents"), and the related mythical beasts dragons. The term worm can also be used as an insult or pejorative term used towards people to describe a cowardly or weak individual or individual seen as pitiable.

Distribution and habitat

Worms live in almost all parts of the world including marine, freshwater, and terrestrial habitats. Some worms living in the ground help to condition the soil (e.g., annelids, aschelminths). Many thrive as parasites of plants (e.g., aschelminths) and animals, including humans (e.g., platyhelminths, aschelminths). Several other worms may be free-living, or nonparasitic. There are worms that live in freshwater, and even on the seashore. Ecologically, worms form an important link in the food chains in virtually all theecosystems of the world.

In the United States, the average population of worms per acre is 53,767.[4]

Classification

In everyday language, the term worm is also applied to various other living forms such as larvae, insects,centipedes, shipworms (teredo worms), or even some vertebrates (creatures with a backbone) such as blindwormsand caecilians. Worms can be divided into several groups, but are still technically decomposers.

The first of these, Platyhelminthes, includes the flatworms, tapeworms, andflukes. They have a flat, ribbon- or leaf-shaped body with a pair of eyes at the front. Some are parasites.The second group contains thethreadworms, roundworms, andhookworms. This phylum is calledNematoda. Threadworms may be microscopic, such as the vinegar eelworm, or more than 1 metre (3 feet) long. They are found in damp earth, moss, decaying substances, fresh water, or salt water. Some roundworms are also parasites. The Guinea worm, for example, gets under the skin of the feet and legs of people living in tropicalThe third group consists of the segmented worms, with bodies divided into segments, or rings. This phylum is called Annelida and the bristle worms of the sea.

In earlier taxonomic classification, all the above were included in the now obsolete group Vermes.

There are hundreds of thousands ofspecies that live in a wide variety of habitats other than soil. Over time this broad definition narrowed to the modern definition, although this still includes several different animal groups. Phyla that include worms include:

Annelida (segmented worms)Arthropoda (inchworms, sometimes called "canker worms") (arrow worms)Gnathostomulid (jaw worms)Hemichordata (acorn/tongue worms)Nematoda (roundworms)Nematomorpha (horsehair worms) (ribbonworms)Onychophora (velvet worms)Phoronida (horseshoe worms)Platyhelminthes (flatworms)Priapulida (phallus worms)Sipuncula (peanut worms)