Hematite Fe2O3 Oxides Group

Physical Features

1. Color- Metallic gray to earthy red.

2. Streak- Bright red.

3. Luster- Metallic.

4. Cleavage-None.

5. Transparency- Opaque.

6. Fracture- Uneven to sudconchoidal.

7. Hardness- 5.5-6.5

8. Forms- Tabular, botryoidal.

9. Crystal system- Hexagonal (rhombohedral).

Hematite is the most important iron oxide in the world. Hematite contains over 70 percent iron. This iron ore is be often found as a covering, or coating, on rocks that are igneous, metamorphic, and those that are sedimentray. When looking for Hematite, look for rocks that hold a reddish, or rust like color to them. It forms as a hydrothermal, or as a secondary mineral by filling in the pocket's and crevice's with it's wonderful metallic luster. Hematite formes are usually tabular, botryoidal, and rhombohedral. Today, the Lake Superior region has the most abundent supplier of Hematite in the U.S.A. Other occurrences can be noted worldwide.

Sodalite Na4A13(SiO4)3CI) Silicates/ Tectosilicates Group

Physical Features

1. Color- Gray, white, blue, green, yellow violet.

2. Streak- Colorless, white, light blue.

3. Luster- Vitreous to greasdy.

4. Cleavage- Poor to distinct.

5. Transparency- Transparent to translucent.

6. Fracture-Uneven to conchoidal.

7. Hardness- 5.5-6.

8. Forms- Granular to Massive.

9. Crystal feature- Cubic.

Sodalite is a rich blue mineral named for it's high sodium aluminum silicate chloride. In mineralogy it maybe classed as a feldspathoid. Sodalite typically occures in massive granular forms, which crystals are relatively rare and are dodecahedral or octahedral. Much of Sodalite is found in veins of dry silica-poor plutonic igneous rocks such as nepheline syenites, pegmatites and phonolites. On the rare occassion may be found in volcanic ejecta and metamorphosed limestones and dolomite. Hackmanite is a rare but highly important variety of Sodalite which has been said to exhibit the ability to change color when exposed to sunlight. These occurrences happen through out the world.

Rock Crystals Si02 Silicates/Tectosilicates Group

Physican Features

1. Color- Colorless.

2. Streak- White.

3. Luster-Vitreous.

4. Cleavage-None.

5. Transparency- Transparent.

6. Fracture- Conchoidal.

7. Hardness- 7.

8. Forms- Prismatic.

9. Crystal system- Trigonal/Hexagonal.

Rock crystal is the colorless variety of quartz. Rock crystals crystalize directly from magma (lava), in pegmatites, and in low temperatures. This is the purest variety of quartz. The crystals can grow to enormous sizes in pegmatites. They also form inside geodes, as crystalline, and microcrystalline quartz. Quartz is a silicon dioxide and is the third most common mineral in the earths crust. This makes quartz an important and essential component of acidic igneous rock's and can be found just about anywhere.

Jade-Nephrite-Jadite Silicates-Inosilicates Group

Physical Features

1. Color- Green, white, gray, bluish, brown.

2. Streak- Colorless.

3. Luster- Greasy.

4. Cleavage-Good.

5. Transparency- Translucent.

6. Fracture- Splintery.

7. Hardness- 6.5-7.

8. Forms- Rare as a crystal

9. Crystal system-Monoclinic

Jade is actually two seperate minerals called Nephrite and Jadite. Nephrite (a member of the amphibole group), which consists of a microcrystaline interlocking fibrous matrix of calcium magnesium-iron rich amphibole. Jadite (a proxene) consists almost entirely of sodium and aluminium rich proxene with interlocking crystal matrix also. Both minerals form is of microcrystaline and generally occur in metamorphic rocks with a higher pressure, Low temperature, but are made up of different silicate minerals. Although Nephrite and Jadite are mainly recovered as pebbles and boulders it can also occure in the rocks which it was originally formed. Large occurrences can be found in Alaska, California, British Columbia, Japan and China.

Howlite Ca2B5Si09(OH)5 Silicates and Carbonates Group

Physical Featureshttp1. Color- White.

2. Streak- White.

3. Luster- Subvitreous.

4. Cleavage- None.

5. Transparency- Translucent to opaque.

6. Fracture- Conchoidal to uneven.

7. Hardness- 3.5.

8. Form-Nodular masses.

9. Crystal system-- Monoclinic.

In 1868 Canadian Chemist Henry Howe discovered the mineral Howlite, hence the name. Howlite is a calcium borosilicate hydroxide, which occurs in continental evaporite deposits. Many times Howlite is found with other borate and evaporite minerals, such as colemanite, ulexite, anhydrite, gypsum, and clays. Some say the Howlite imitates the mineral turquiose, especially when dyed. California and Canada hold the largest deposit's of Howlite, but can be found all over the world.

Petrified wood

Physical Featuhttp

1. Color- Brown, gray, red, yellow.

2. Streak- White.

3. Luster- Waxy, vitreous, dull.

4. Cleavage- None.

5. Transparency- Transparent to opaque.

6. Fracture- Conchoidal.

7. Hardness- 7.

How does a tree become petrified? About 200 million year's ago when the dinosaurs roamed the earth, large tree's somewhat like the modern day conifer's grew abundant. As the tree's aged and died off, they fell to the ground to lay. Eventually the tree's were swept away by raging flood water's, river's, and lake's. Many of these tree's decomposed quickly, but for others, they were buried deep into massive amounts of oxygen free sediments. The lack of oxygen in the sediments causes the decaying process to slow. The sediment covering the tree's is rich in silica, and volcanic ash, and over a period of time the minerals began to dissolve in the water that seeped through the sediment. This allows the mineral's to absorb within the porous wood. After thousands of years crystalization starts forming in the cellular structure replacing the organic material with Quartz, chalcedony, and jasper. This is called petrification, even today we cannot fully understand the process of fossilization of tree's. Petrified wood's coloring comes from the impurities present in the wood during fossilization, some of these impurities may be caused by manganese ,iron, lithium, and copper. Petrified wood is considered pseudomorph. Pseudomorphs are minerals which change in their chemical composition, but remain in their original state. One of the largest deposits of petrified wood is found at Arizona's Petrified Forest National Park.