Opal!
33 videos
Updated 7 days ago
Opal is a hydrated amorphous form of silica (SiO2·nH2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt.
The name opal is believed to be derived from the Sanskrit word upala, which means 'jewel', and later the Greek derivative opállios.
There are two broad classes of opal: precious and common. Precious opal displays play-of-color (iridescence); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to diffract light, resulting in play-of-color. Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. Black opal is considered the rarest, while white, gray, and green opals are the most common.
-
Robbed! Grabbed the wrong half!
RyanzRocksThis rock appears to be a type of **thunder egg**. Here's why: 1. **Coloration and Banding**: The rock shows a combination of colors, including brown, white, green, and possibly some hints of other colors, which is typical for agates and thunder eggs. The banding pattern is also characteristic of agates, which form in cavities of volcanic rocks. 2. **Translucency**: Some parts of the rock are translucent, which is common in agates due to their chalcedony composition. 3. **Texture**: The rock's texture looks somewhat waxy or glassy, which is typical for agates that have been polished or naturally worn smooth. 4. **Inclusions**: The yellowish or brownish areas could be due to iron oxide or other mineral inclusions, which are often found in agates. Thunder eggs are nodules of agate found in volcanic rocks, and they often have a hollow or partially hollow interior filled with crystals or banded agate.25 views -
Thunderegg Cut w/Opal!
RyanzRocksThese rocks appears to be a type of **thunder egg**. Here's why: 1. **Coloration and Banding**: The rock shows a combination of colors, including brown, white, green, and possibly some hints of other colors, which is typical for agates and thunder eggs. The banding pattern is also characteristic of agates, which form in cavities of volcanic rocks. 2. **Translucency**: Some parts of the rock are translucent, which is common in agates due to their chalcedony composition. 3. **Texture**: The rock's texture looks somewhat waxy or glassy, which is typical for agates that have been polished or naturally worn smooth. 4. **Inclusions**: The yellowish or brownish areas could be due to iron oxide or other mineral inclusions, which are often found in agates. Thunder eggs are nodules of agate found in volcanic rocks, and they often have a hollow or partially hollow interior filled with crystals or banded agate.17 views -
Thundereggs?
RyanzRocksThese rocks appears to be a type of **thunder egg**. Here's why: 1. **Coloration and Banding**: The rock shows a combination of colors, including brown, white, green, and possibly some hints of other colors, which is typical for agates and thunder eggs. The banding pattern is also characteristic of agates, which form in cavities of volcanic rocks. 2. **Translucency**: Some parts of the rock are translucent, which is common in agates due to their chalcedony composition. 3. **Texture**: The rock's texture looks somewhat waxy or glassy, which is typical for agates that have been polished or naturally worn smooth. 4. **Inclusions**: The yellowish or brownish areas could be due to iron oxide or other mineral inclusions, which are often found in agates. Thunder eggs are nodules of agate found in volcanic rocks, and they often have a hollow or partially hollow interior filled with crystals or banded agate.19 views -
Thundercup glow!
RyanzRocksThese rocks appears to be a type of **thunder egg**. Here's why: 1. **Coloration and Banding**: The rock shows a combination of colors, including brown, white, green, and possibly some hints of other colors, which is typical for agates and thunder eggs. The banding pattern is also characteristic of agates, which form in cavities of volcanic rocks. 2. **Translucency**: Some parts of the rock are translucent, which is common in agates due to their chalcedony composition. 3. **Texture**: The rock's texture looks somewhat waxy or glassy, which is typical for agates that have been polished or naturally worn smooth. 4. **Inclusions**: The yellowish or brownish areas could be due to iron oxide or other mineral inclusions, which are often found in agates. Thunder eggs are nodules of agate found in volcanic rocks, and they often have a hollow or partially hollow interior filled with crystals or banded agate.31 views -
Thunderegg glow!
RyanzRocksThese rocks appears to be a type of **thunder egg**. Here's why: 1. **Coloration and Banding**: The rock shows a combination of colors, including brown, white, green, and possibly some hints of other colors, which is typical for agates and thunder eggs. The banding pattern is also characteristic of agates, which form in cavities of volcanic rocks. 2. **Translucency**: Some parts of the rock are translucent, which is common in agates due to their chalcedony composition. 3. **Texture**: The rock's texture looks somewhat waxy or glassy, which is typical for agates that have been polished or naturally worn smooth. 4. **Inclusions**: The yellowish or brownish areas could be due to iron oxide or other mineral inclusions, which are often found in agates. Thunder eggs are nodules of agate found in volcanic rocks, and they often have a hollow or partially hollow interior filled with crystals or banded agate.34 views 1 comment -
Beautiful dark opal!
RyanzRocksOpal is a hydrated amorphous form of silica, with a water content typically between 3 and 21% by weight, most commonly around 6-10%. It's deposited at relatively low temperatures and can be found in the fissures of various rock types, including limonite, sandstone, rhyolite, marl, and basalt. Here's a deeper look into opal: Types of Opal: Precious Opal: Known for its "play-of-color," which is an optical phenomenon where colors flash or change as the angle of light or observation changes. This effect is due to the diffraction of light through the microscopic silica spheres within the opal. Common Opal: Lacks the play-of-color and can come in a variety of colors like white, black, grey, yellow, orange, red, or brown. It's often referred to as "potch" when not gem-quality. Fire Opal: Typically ranges in color from yellow to orange to red and can be transparent to translucent. Fire opals can exhibit play-of-color, but their name comes from the fiery body color. Boulder Opal: A type of opal naturally attached to its host rock. It's often cut with the host rock to provide stability and to enhance the visual appeal. Matrix Opal: The opal fills the cracks and cavities within the host rock, creating a network of opal that's visible on the surface. Formation: Primary Opal: Forms through the slow deposition of silica from groundwater in cavities or fractures of rocks. Secondary Opal: Can form by weathering or alteration of other minerals, often in more superficial environments or through the action of silica-rich waters. Locations: Australia: The world's leading source, especially for precious opal, with significant deposits in places like Coober Pedy, Lightning Ridge, and White Cliffs. Ethiopia: Known for its black opals and more recently discovered opal fields. Mexico: Famous for fire opals. Brazil: Produces a variety of opals, including crystal opal. Properties: Hardness: Typically ranges between 5.5 to 6.5 on the Mohs scale, though it can be softer if less hydrated or harder if more silica-rich. Luster: Can range from waxy to resinous to vitreous. Transparency: Varies from opaque to semi-translucent to transparent.8 views -
It's curved!
RyanzRocksPlume agate is a variety of chalcedony, a microcrystalline quartz, characterized by delicate, plume-like inclusions of various colors and minerals. These inclusions often resemble feathers, flowers, or flames, giving the agate a unique and visually appealing appearance. Plume agate only forms in hotsprings with the help of thermophiles and extremophiles (microscopic organisms that like harsh and hot environments) collecting silica and other dissolved particles in silica rich hotsprings and depositing them in wild patterns within the agate. A combination of clays, metals and minerals make up the cool colors and textures we experience. There are many famous deposits of plume, flame and other varieties of textures made with the assistance of microbes.7 views -
Botryoidal formations!
RyanzRocksPlume agate is a variety of chalcedony, a microcrystalline quartz, characterized by delicate, plume-like inclusions of various colors and minerals. These inclusions often resemble feathers, flowers, or flames, giving the agate a unique and visually appealing appearance. Plume agate only forms in hotsprings with the help of thermophiles and extremophiles (microscopic organisms that like harsh and hot environments) collecting silica and other dissolved particles in silica rich hotsprings and depositing them in wild patterns within the agate. A combination of clays, metals and minerals make up the cool colors and textures we experience. There are many famous deposits of plume, flame and other varieties of textures made with the assistance of microbes.7 views -
Jasper, Chalcedony, Opal & ???
RyanzRocksThis rock has characteristics that suggest it could be a type of brecciated jasper or agate. Here are the reasons for this identification: Texture and Appearance: The rock has a mix of colors, predominantly white with patches of brown, red, and possibly some darker inclusions. This mottled appearance with different colored sections embedded within a matrix is typical of brecciated materials. Brecciation: The rock appears to have a brecciated texture, where there are fragments of one material (likely agate or jasper) embedded in a matrix of another. This can happen due to geological processes like faulting or intense weathering. Silica Content: Jasper and agate are both forms of chalcedony, which is a type of silica. The shiny, somewhat translucent appearance of parts of the rock aligns with the properties of chalcedony. Commonality: Jasper and agate are common and widely found, often appreciated for their decorative qualities due to their color and pattern. If this rock was found in a specific location known for certain types of rocks, or if you're looking for a more precise identification, details about its origin or taking it to a local geologist or gemologist could provide more accurate information. However, based on the visual characteristics from the image, brecciated jasper or agate seems a likely identification.25 views -
Chalcedony or Opal!?
RyanzRocks#Chalcedony is a cryptocrystalline form of silica, much like chert, but it's distinguished by its fibrous microcrystalline structure. Here are the key features of chalcedony: Composition: Silica (SiO₂): Like chert, it's primarily composed of quartz, but the structure of the crystals is different. Texture and Structure: Microcrystalline: The individual crystals are too small to be seen with the naked eye. Fibrous: Chalcedony often displays a fibrous or acicular (needle-like) structure in contrast to the more blocky or mosaic structure of other quartz varieties like chert. Varieties of Chalcedony: Agate: Known for its banded or layered appearance; each band often has a slightly different color. Jasper: Similar to chalcedony but typically more opaque and can contain significant impurities like iron, giving it a wide range of colors. Onyx: Usually refers to chalcedony with parallel bands of black and white, though the term can be misused for other banded chalcedonies. Carnelian: A reddish variety due to iron oxide impurities. Chrysoprase: Colored green by nickel silicate inclusions. Bloodstone (Heliotrope): A dark green chalcedony with red spots of iron oxide or hematite. Physical Properties: Hardness: 6.5 to 7 on the Mohs scale, slightly softer than quartz but still quite durable. Luster: Waxy or greasy when polished. Transparency: Can range from translucent to nearly opaque. Fracture: Conchoidal, similar to chert, but due to its fibrous nature, it can show a splintery fracture in some cases.21 views