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Daily Lesson #6

Student's Name:

Renton

Student's ID:

Renton46

No Help:

First Question:

Nesosilicates are silicates with independent SiO4 tetrahedral. They do not link with other SiO4 groups.

Second Question:

Garnets are nesosilicates with a structural formula of A3B2(SiO4)3. The A sites are 8 coordination cation sites holding large divalent cations, while the B are 6 coord. cation sites holding smaller trivalent cations. A sites can be filled by Ca, Mn, or Fe2+. B sites canÝ be filled by Al3+, Fe3+, or Cr3+.

Third Question:

Comments about Assignment

i like this stuff, it seems relatively clear.

Student's Name:

Cutter

Student's ID:

Cutter

No Help:

First Question:

Neso-silicates are comprised of independent tetrahedral SiO4 groups. The tetrahedra are not linked to each other. They are only bound to each other via an ionic bond within their interstitial cations.Ý This structuring , thus relies heavily on the size and charge of the cations.Ý The atomic packing of these structures is generally dense which results in a high specific gravity and hardness.Ý In additon, the independent linkages result in a lack of cleavage.

Second Question:

A3B2(SiO4)3

The A-site consists of an 8-coordinated cationic site. These molecules are rather large divalent cations.Ý This creates a well defined division for elements substituting in this site. The two divisions are those with Ca and those that appeal to the easily interchangable Mg 2+, Fe 2+, and Mn 2+.

The B-sites are comprised of 6-coordinated cationic sites. This site is occupied by smaller trivalent cations.Ý Just as in the A-sites, the substitions result in a seperation of garnets into Al 3+, Fe 3+, and Cr 3+

The composition of these sites creates a specific 2 group classification in the garnet group.

Third Question:

Comments about Assignment

Student's Name:

Williams

Student's ID:

Williams69

No Help:

First Question:

Tetrahedra are isolated in nesosilicates, bonded only by ionic bonds from interstitial cations.Ý Because the tetrahedra aren't linked, the crystal habit is equadimensional and they lack cleavage planes.Ý Due to the interstitial ions, there is iregularity in the coordination of the polyhedra.

Second Question:

A3B2(SiO4)3

A site possibilities include Ca, Fe, Mg, and Mn.Ý B site substitutions include Al , Fe, and Cr.

PyropeÝÝÝÝÝÝÝÝÝ Mg3Al2Si3O12

AlmandineÝÝÝÝÝÝ Fe3Al2Si3O12

SpessartineÝÝÝÝ Mn3Al2Si3O12

UvaroviteÝÝÝÝÝÝ Ca3Cr2Si3O12

GrossularÝÝÝÝÝÝ Ca3Al2Si3O12

AndroditeÝÝÝ ÝÝÝCa3Fe2+Si3O12

Third Question:

Comments about Assignment

Student's Name:

Vanover

Student's ID:

vanover16

No Help:

First Question:

All neso-silicates have (SiO4) tetrahedrons which are unbonded to other tetrahedrons. They have a structure that produces stronger bonds and a closer packing of ions and therefore a higher density, index of refraction and hardness than chemically similar silicates in other subclasses. Consequently, there are more gemstones in the nesosilicates than in any other silicate subclass.

Second Question:

The general formula is A-B-(Si04)3.

A-site substitutions are Fe3, Ca3, Mg3, and Mn3.

B-site substitutions are Al2, Fe2, and Cr2.

Third Question:

Comments about Assignment

Student's Name:

Wood

Student's ID:

Wood95

No Help:

First Question:

In nesosilicates the SiO4 tetrahedra are isolated and bound to each other only by ionic bonds from interstitial cations.Ý This means that the SiO4 tetrahedra are independent and not linked into chains or sheets, and the crystal habit of nesosilicates is equidimensional and pronounced cleavage directions are absent.

Second Question:

general formula: A3B2(SiO4)3

substitutions:

A-site: (Pyralspite)ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ

Mg3Al2Si3O12 (pyrope)

Fe3Al2Si3O12 (almandine)

Mn3Al2Si3O12 (spessartine)

B-site:Ý (Ugrandite)

Ca3Cr2Si3O12 (Uvarovite)

Ca3Al2Si3O12 (Grossular)

Ca3Fe2 3+Si3O12 (Andradite)ÝÝ

Third Question:

Comments about Assignment

i have really liked the labs--they're not too hard, but i still definitely learn stuff.Ý thanks, i never like labs!

Student's Name:

Spalt

Student's ID:

Spalt73

No Help:

First Question:

The Si04 tetrahedra are only bonded to each other by ionic bonds.Ý There is no sheeting or linkage other than that.Ý They tend to have dense packing with high specefic gravity and hardness.Ý

Second Question:

A3B2(SiO4)3

A: Ca, Mg, Fe2+, Mn2+

B: Al, Fe3+, Cr3+

Third Question:

Comments about Assignment

Student's Name:

Angstmann

Student's ID:

Angstmann18

No Help:

First Question:

All of the structures consist of tetrahedrals in different arrangements.Ý

Second Question:

A3B2(SiO4)3 is the general garnet formula.Ý In the A site, Ca, Mg, Fe+2, and Mn+2 are possible substitutions.Ý In the B site, Al, Fe+3, and Cr+3 are the possible substitutions.

Third Question:

Comments about Assignment

Student's Name:

gilbert

Student's ID:

gilbert62

No Help:

First Question:

The structure of the neso-silicates is dense, which causes a them to have a relatively high specific gravity and hardness.Ý No pronounced cleavage and they are generally equidimensional.

Second Question:

A3B2(siO4)

A sites occuopied by large divalent cations (Ca, Mg 2+, Fe2+ Mn2+)

With all ions but Ca interchangable.

B sites are occupied by small trivalent cations (Al3+ Fe3+Ý cr3+)

Third Question:

Comments about Assignment

IÝ found the text to be redundant in several different places.Ý I feel lost in the amount of words thrown at us at once.

Does divalent the ion has given up two electrons... and trivalent 3?

Student's Name:

TRAUB

Student's ID:

Traub70

No Help:

First Question:

They are all made up of tetrahedrals in different arrangements

Second Question:

The general structural formula is A3B3(SiO4) where the A sites can house Ca, Mg, Fe2+, or Mn2+ and the B sites house Al, Fe3+, and Cr3+

Third Question:

Comments about Assignment

Student's Name:

Caudill

Student's ID:

Caudill22

No Help:

First Question:

The structure of garnet consists of alternating SiO4 tetrahedra and BO6 octahedra that share corners to form a continuous three-dimensional network.Ý The A sites are surrounded by eight oxygens in irregular coordination polyhedra.

Second Question:

Garnet compositions can be expressed by the general structural formula A3B2(SiO4)3 where the A site houses Ca, Mg, Fe2+ or Mn2+ and the B site incorporates Al, Fe3+, and Cr3+.

Third Question:

Comments about Assignment

I started reading Ch. 13 and realized that this chapter is over 100 pages long.Ý How far do we need to proceed into the chapter?

Student's Name:

Porfidio

Student's ID:

Porfidio93

No Help:

First Question:

Ý Since packing for nesosillicate structures is dense, the most distinguishing structural characteristic is the relatively high specific gravity and hardness of this mineral group.

Second Question:

The general formula is:Ý A3B2(SiO4)3

A-sites can have Ca, Mg2+, Fe2+, or Mn2+

B-sites can have Al3+, Fe3+, or Cr3+

This creates two series of garnets, the pyralspite(Ca absent in A; B=Al) and ugrandite(A=Ca).Ý The pyralspite series includes:Ý Pyrope (Mg3Al2), Almandine (Fe3Al2), and Spessartine (Mn3Al2).Ý For the ugrandite series, the minerals are:Ý Uvarovite (Ca3Cr2), Grossular (Ca3Al2), and Andradite (Ca3Fe2 3+).

Third Question:

Comments about Assignment

Student's Name:

Williams

Student's ID:

Williams94

No Help:

First Question:

The most distinguishing structural characteristic of the nesosilicates, is that their atomic packing is very dense, making them extremely hard and giving them a relatively specific gravity.Ý

Second Question:

A3B2(SiO4)3 is the general formula for the garnet group.Ý

The division of garnets is definied as being those with Ca and those with ions that are able to substitute themselves for others.Ý The possible "substitutions" are given two series: pyralspite which are lacking Ca and there B voids are filled with Al; whereas, the other series is the ugrandites which are defined as being filled with Ca always in their A voids.Ý

Third Question:

Comments about Assignment

Student's Name:

Ratliff

Student's ID:

Ratliff06

No Help:

First Question:

Neso-silicates are distiguishable by binding to each other through ionic bonds.Ý In addition, the tetrahdra are independent and not linked into chains or sheets.Ý It is generally equidimensional and there are no cleavage directions apparent.

Second Question:

A3B2(SiO4)3Ý The A-site can be filled with Ca, Mg +2, Fe+2, Mn +2, due to sizeÝ limitations.Ý The B-site can be filled with Al +3, Fe +3, and Cr +3, also due to size restrictions.Ý These possibilities are grouped into two categories: Pyralspite and Ugrandite.Ý Another B-site grouping is :Ý aluminum garnets, ferri-garnet, chrome-garnet

Third Question:

Comments about Assignment

Student's Name:

kerr

Student's ID:

149

No Help:

First Question:

Neso silicates are single tetrahedrons meaning SiO4 is not bonded to any other tetrahedrons.Ý Since they are single tetrahedrons thier bonds are stronger and closer packed than other silicates.

Second Question:

A3B2(SiO4)3

In the A site there is substitutions of divalent metals.Ý In the bi site the substitution is between trivalent metals.

Third Question:

Comments about Assignment

Student's Name:

Harlacker

Student's ID:

Harlacker27

No Help:

First Question:

The most important structural characteristic of the nesosilicate minerals -- garnets, olivines, and alumino-silicates -- is the arrangement of their silica tetrahedra.Ý Specifically, their tetrahedra occur in isolation, and are not linked to other tetrahedra.Ý Instead they are bound together through ionic bonds to the cations that occur in the interstices between the tetrahedra.

Second Question:

The general formula for the garnet group is A3B2(SiO4)3.Ý Cations occurring in the A site are Ca, Mg, Fe2+, and Mn2+.Ý Those occurring in the B site are Al, Fe3+, and Cr3+.Ý

Third Question:

Comments about Assignment

Student's Name:

lentz

Student's ID:

lentz02

No Help:

First Question:

olivine- Mg2SiO4

alumino- Al2SiO5

garnet- Ca3Al2Si3O12

The most distingusing characteristic between the neo-silicates is that they all are formed from ionic bonds forming tetrahedrals.

Second Question:

A3B2(SiO4)

Subsitutions for A can be Mg, Fe, Mn, and Ca.

Subsitutions for B can be Al, Cr, and Fe.

Third Question:

Comments about Assignment

Student's Name:

mccall

Student's ID:

mccall99

No Help:

First Question:

SiO4 tetrahedra are isolated and bound to eachother only by ionic bonds from interstitial cations.Ý Structures depend on size and charge of atoms.Ý they also have a similar high specific gravity and hardness.

Second Question:

the general formula for the garnet group is A3B2(siO4)3Ý where A and B refer to 8 and 6 coordinate cationic sites.Ý one possible substitution in the a and b sites is that hydroxyl can substitute for SiO4.

Third Question:

Comments about Assignment

Student's Name:

wingate

Student's ID:

wingate84

No Help:

First Question:

Individual silica tetrahedra linkeed to each other by other cations(than Si).

Second Question:

A3B2(SiO4)3 is the formula for the garnet group. A site substitutions: Mg, Fe, Mn, Ca. B site substitutions: Al, Cr, Fe.

Third Question:

Comments about Assignment

Student's Name:

Swan

Student's ID:

Swan41

No Help:

First Question:

These minerals all have the distinguishing characteristic of having two cationsÝ (ex. Al2 or Mg2) bonded to the silicate group.

Second Question:

There can be substitutions for the a dn b sites of ions that are of similar radius and charge.

Third Question:

Comments about Assignment

Student's Name:

Voakes

Student's ID:

voakes47

No Help:

First Question:

The SiO4 tetrahedra are isolated.Ý The are bound with ionic bonds only.Ý

Second Question:

A3B2(SiO4)3.Ý The A site can house Ca Mg, Fe2+, or Mn2+.Ý The B site can house Al, Fe3+, or Cr3+.Ý

Third Question:

Comments about Assignment

Sorry this is so late.Ý For some reason the test in this class (and tests in others) made it completely skip my mind.Ý