A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Types of Boulders

Basalt
Basalt

Basalt underlies more of Earth's surface than any other rock type. Most areas within Earth's ocean basins are underlain by basalt. Although basalt is much less common on continents, lava flows and flood basalts underlie several percent of Earth's land surface.

source: geology.com
Carbonates eg Calcite, Magnesite, Dolomite
Carbonates eg Calcite, Magnesite, Dolomite

Dolomite is a mineral which contains calcium magnesium carbonate CaMg(CO 3) 2 mainly. Dolomites can grow up to large sizes forming mineral beds, and this is a sedimentary rock forming mineral. Dolomite is widely distributed all over the world and commonly found in sedimentary rocks.

Granite
Granite

Strictly speaking, granite is an igneous rock with between 20% and 60% quartz by volume, and at least 35% of the total feldspar consisting of alkali feldspar, although commonly the term "granite" is used to refer to a wider range of coarse-grained igneous rocks containing quartz and feldspar.

Halides eg
Halides eg

Evaporite minerals are those that form by coming out of solution when seawater and the waters of large lakes evaporate. Rocks made of evaporite minerals are sedimentary rocks called evaporites. Halides are chemical compounds that involve the halogen (salt-forming) elements fluorine and chlorine ...

source: thoughtco.com
Hydroxides eg Goethite, Brucite
Hydroxides eg Goethite, Brucite

Although Brucite is generally a common mineral, specimens worthy of collection only come from a handful of locations worldwide. In Italy, light blue crystal plates have come from the Val di Serra Quarry, Pilcante, Trento Province, Italy.

source: minerals.net
Limestone
Limestone

Like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of marine organisms such as coral or foraminifera. These organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die.

image: vizpark.com
Marble
Marble

Ruby in Marble: Marble is often the host rock for corundum, spinel, and other gem minerals. This specimen is a piece of white marble with a large red ruby crystal from Afghanistan. Specimen is about 1 1/4 inches across (about 3 centimeters).

source: geology.com
Native Elements
Native Elements

In the iron group, the element nickel is the same size as iron (has the same atomic radii) and can substitute for some of it. This is known as a solid-solution. Iron-nickel solid solutions are found in metrorites and compose a large part of the Earth's core.

Oxides eg Corundum (Incl Sapphire), Hematite, Spinel
Oxides eg Corundum (Incl Sapphire), Hematite, Spinel

Oxides. eg corundum (incl. sapphire), hematite, spinel. Hydroxides. eg. Goethite, brucite. Sulfides. eg. Pyrite, galena, sphalerite. Sulfates. eg. Baryte, gypsum. Carbonates. eg. Calcite, magnesite, dolomite. Phosphates. eg. Apatite, monazite. Halides. eg. Fluorite, halite (rock salt). Silicates (most common) Orthosilicates. eg. Garnet, olivine.

source: qm.qld.gov.au
Phosphates eg Apatite, Monazite
Phosphates eg Apatite, Monazite

Monazite is a rare phosphate mineral with a chemical composition of (Ce,La,Nd,Th)(PO4,SiO4). It usually occurs in small isolated grains, as an accessory mineral in igneous and metamorphic rocks such as granite, pegmatite, schist, and gneiss.

source: geology.com
Quartzite
Quartzite

The name "quartz arenite" is a more appropriate and less confusing name for these rocks. It is often difficult or impossible to differentiate quartz arenite from quartzite. The transition of sandstone into quartzite is a gradual process.

source: geology.com
Sandstone
Sandstone

What is Sandstone? Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.

source: geology.com
image: msnb.co.za
Slate
Slate

However, slate occurs in a variety of colors even from a single locality; for example, slate from North Wales can be found in many shades of grey, from pale to dark, and may also be purple, green or cyan.

Sulfates eg Baryte, Gypsum
Sulfates eg Baryte, Gypsum

Barite is barium sulfate (BaSO 4), a heavy mineral that commonly occurs as concretions in sedimentary rocks. In the loose sandstones of Oklahoma, barite forms "roses" like these. They're similar to gypsum roses, and sure enough, gypsum is also a sulfate mineral.

source: thoughtco.com
image: rlayton.net
Sulfides eg Pyrite, Galena, Sphalerite
Sulfides eg Pyrite, Galena, Sphalerite

Pyrite, iron sulfide (FeS 2), is a common mineral in many rocks. Geochemically speaking, pyrite is the most important sulfur-containing mineral. (more below) Pyrite occurs in this specimen in relatively large grains associated with quartz and milky-blue feldspar. Pyrite has a Mohs hardness of 6, a brass-yellow color and a greenish black streak.

source: thoughtco.com