half pound silver dollarWe are frequently asked “Is this silver?”

Various regulations are in effect regarding the marking of sterling silver jewelry. The first law regulating the stamping of silver products was enacted by the Massachusetts legislature in 1894 followed by several other states before the National Stamping Act was passed by Congress in 1906 and put into effect in June 13, 1907. This law, enhanced and amended several times over the years, provides the basis for regulating the marking and stamping of silver products.

Sterling Silver is 92.5% silver and 7.5% copper. Jewelry made from pure silver would wear more quickly, as pure silver is quite soft. Sterling components and jewelry made in the USA are often stamped Sterling. Goods made for international trade are often marked .925 indicating 92.5% fineness.

The 1906 act required that any product marked "sterling" or "coin" must contain 925 per 1000 parts pure silver for "sterling" and 900 per 1000 parts pure silver for "coin" silver, permitting a divergence of only 4 parts per 1000 from this standard. An amendment in 1961 required also the maker's trademark to be stamped next to the silver standard mark.

Mexican Silver, German Silver, Indian Silver, Montana Silver, or simply Silver do not guarantee any silver content. German Silver is another name for the alloy of Copper, Nickel and Zinc usually called Nickel Silver. Nickel Silver contains no silver.

In many countries, precious metal must be stamped with a quality mark such as .925 for sterling. Some countries require that jewelry of precious metal be submitted to a governmental assay office for appropriate testing before being marked and sold.

In the USA, The National Gold and Silver Marketing Act DOES NOT require precious metals to be marked with quality. However, if a quality mark is used, the National Stamping Act, as amended, not only requires the use of trademarks, but also specifically requires the registration of such a trademark with the U.S. Patent and Trademark Office (PTO). In spite of the law, many regularly used marks on American jewelry are not yet registered trademarks.

If in doubt as to whether your unmarked jewelry is silver vs. silver plate vs. bright nickel plate, you can try a couple of simple tests. Silver oxidizes readily (remember your mom’s blackish-looking teapot?). Rubbing the item with a clean white cloth should produce a black stain on the cloth, identifying it as silver or silver plated. Sterling is not magnetic, so if the piece is attracted to a magnet it is not sterling. Bright nickel is simply too “shiny”- it lacks the duller appearance of sterling.

Yellowstone Petrified Wood

As volcanic activity often provides conditions for petrification, one might surmise Yellowstone National Park to be a good laboratory in which to study the mechanics of the process.

That would be an apt conclusion. Yellow National Park has probably the highest concentration of petrified wood anywhere, with by some estimates, 27 or more separate petrified layers spanning three thousand vertical feet.

The process is easy to visualize; an eruption buries a forest, and thousands or millions of years elapse during which the trees are petrified. As the covering gives rise to another forest layer, another eruption buries this one. And so the process continues for millions of years.

Trees have been found petrified in vertical and horizontal positions. Horizontal trees may have been covered in mudslides, or transported by flood waters to a different location. Vertical trees may simply have been covered by ejecta and fossilized where they stood.

Species of extant trees found in Yellowstone include maple, redwood, birch, hickory, pine, Sago palm, oak. elm, willow, sycamore, and other species, some now extinct. The variety of species attests to the varying climate YNP has seen over millions of years.

The caldera where Yellowstone Lake formed is that of a dormant super volcano. A super volcano is defined as a volcano ejecting 1000 or more cubic kilometers (240 cubic miles) of material. As a comparison, the 1980 eruption of Mt. St. Helens ejected 0.3 cubic kilometers of material. Yellowstone has erupted three times in the last two million years. There have been no super volcano eruptions in historic times. The effects of a super volcano eruption would be felt worldwide.

How to spot a fake fossil

With the increasing rarity and desirability of fossils, it is only to be expected that fake fossils find their way on the market. In many cases the degree of counterfeiting is so good even the experts are fooled. This is unfortunate. We have discontinued several popular items simply because we are unable to verify their authenticity.

Two countries known for fossil fakery are Morocco and China. It is illegal to export fossils from China, so nearly everything you see on the market from China is a replica or fake. It should be noted that in general one nation does not necessarily enforce the export regulations of another. So, once a legitimate fossil escapes the nation of origin, it is not necessarily illegal to buy or sell the item. Many nations have rules against exporting fossils. In general, the better a fossil looks, the higher the likelihood of it being fake- if it looks too good to be true, it probably is.

Any fossils purchased from Cooke City Rocks is guaranteed to be authentic.

Dino Dung?

The correct name is coprolite, or fossilized feces (animal waste). Our specimens come from Utah. Many rough coprolite specimens from this area are ten pounds or more, so we are talking about reasonably large animals.

It is usually not possible to determine the species of the animal producing the specimen, so emphatic claims about a specimen being genuine dinosaur dung should be viewed skeptically. Coprolite may in fact be from any species-marine creatures, amphibians, or mammals. So the specimen you have may be from a prehistoric horse, giant sloth, dinosaur, mammoth, etc. However, it is possible to take an educated guess as to what species produced the dung based on species known to have inhabited the area where the dung was found, or sometimes by an analysis of the specimen. Coprolites found in bone beds are probably from the fossilized bones of creatures found in the bed.

If the coprolite contains fossilized swamp creatures, plant matter, or animal bones, sinew, etc., one could deduce the animal to be an herbivore, carnivore, or marsh-dweller. The colors vary, depending upon the mineral content of the soil and ground water present during the fossilization process. The colors are not related to what the animal had for breakfast!

One of the most famous coprolites came from Saskatchewan, Canada, and measured seventeen inches by six inches in diameter, shaped pretty much like you’d expect. The specimen contained bone fragments and paleontologists think it may have been from a T.Rex, whose bones have been found in the area.

Montana Moss Agates: Montana's State Rock

The Montana Moss Agates are each one of a kind. Iron oxides tint the agates to red and manganese spread into layers making the famous black dendrite tree and flower patterns. Internal botryoidal patterns often show as bubbly cloud like formations on highly polished specimens.

The Montana Moss Agates formed over 65 mission years ago as volcanoes began erupting along the eastern front of what is now the Rocky Mountains. For millions of years massive lava flows buried the land including entire forests. Most agates from around the world, including the Montana Moss Agates, were formed within cavities and gas pockets within the lava. Most of these cavities were caused by trapped steam and gasses trying to escape through the lava as the lava cooled. Mineral water with silica (SiO2) flowed in and out of these cavities leaving behind layer after layer of agate.

Between 40 and 50 million years ago the central Montana Mountains were forming. The lifting and shifting movement of the continental plate caused the break up of the original lava beds containing the agate nodules, limb casts and petrified wood. For tens of millions of years the harder agates eroded out of the softer basalt. During the last 2 million years glaciers and rivers carried the agates east along a wide basin, where the Yellowstone River now flows.

Cooke City Rocks has a good selection of Montana Moss agates.

Coming in 2018

We anticipate a limited selection of new items...

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