hand2mouthmining
spending too much on rocks
Purveyors of California Gem Rock
Member since September 2011
Posts: 495
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Post by hand2mouthmining on Dec 27, 2012 17:50:50 GMT -5
whatever it is, I think it is pretty cool looking. I like those big chunks. Thanks, B! We love the Blue G and agree with you. Feel free to contact me if you'd like to try some. We'll keep it affordable. my apologies - I thought you had been getting 'into it' with the petrologists. Take my thoughts to your specialists and let them chew it over and see what they think. Metalsmith, no apologies necessary. My intent in starting this thread was to announce to our Blue G customers the GIA Identification Report findings. Its gone much farther than intended, and in directions that sometimes were not helpful. I'd prefer to discuss it in a different way now. Perhaps you would like to start another thread for discussion? If talented geo-enthusiasts wish to examine and discuss the material, I'll take part, but I'm not trained or qualified to do the petrological research. As for the petrologists, they're like me ... They need to make a living. When we can afford more lab work, we'll do it. The cost of what we've had done was equal to 2 months of my work gasoline costs, for the pleasure of giving ourselves and our customers information. If folks want to see more commercial lab work done on Blue G, we welcome them to purchase some, and help us to pay for it! BTW, we have lots of good, hard Navy Blue blueschist, some with the classic garnet association, some with chrysotile & amphibole, some with sparkly mica ... Fun cabbing rock. I'll post photos of cabs, soon. Hi, Kris! I think the Blue G is gorgeous cabbing material and I've seen some beautiful cabs that Lloyd has produced from it (he loves it! ), but I am confused about the Blue G being called "Gem-grade Lawsonite." From what I read in the GIA gem report on the cabochon and rough you submitted, the Blue G has primarily not only Lawsonite, but also (primarly consists of) Feldspar and Quartz, along with other minerals in it. I'm not an expert, but unfortunately I agree with a few others that the Blue G shouldn't be called nor advertised as "Gem-grade Lawsonite," or "Lawsonite" since the GIA gem report states otherwise. Maybe if further testing is done on Blue G, then you could confirm whether or not it's Lawsonite or what it should be properly called. This is suggested in the "comments" section of the GIA gem report. Have you posted the GIA gem report on the Gemology Online forum for review? Here's some faceted gem-grade Lawsonite I found on Steve Perry's site: www.steveperrygems.com/gems/raream.html I looked over your site, and hope to see some chiastolite specimens, and cut materials on it soon! I love that stuff!! Hi, Jan! Thanks for the note. Your suggestions are appreciated. For the time being, we're calling our cutting grade conglomerate rock with a primary Lawsonite component, this: Blue G, Panoche Hills Gem Lawsonite. We have to call it something to market it, and "Red Bull" was already taken. Gemologists I've spoken to find that acceptable as a trade name. It is not meant to be a scientific identification. It's meant to identify our material, while providing a location based category for other miners and vendors to use with similar material. They can drop the "Blue G" if they like, and call it "Marvin" or something else if they prefer. If I really wanted to argue the point, I'd point to Turquoise, which is called that even when it contains a high percentage of associated minerals such as cuprite and other copper "ides", or even gold. I'm tired of arguing, so I won't ... Darn! Just did! As far as we know, it's the first primary Lawsonite conglomerate commercially available in quantity for lapidary use. Thanks for pointing me to Steve Parry's site, his offerings quadrupled the number of faceted Lawsonite crystals I've seen. Personally, I wouldn't buy one, I'm mostly a cab guy. His cabbed example is nice, and within the range of our Lawsonite conglomerate, perhaps a bit darker blue, with a great polish. Note, he lists it as "rare", and SOLD. This will be my last post to this thread. I'm finally starting to get over the nasty Flu (crossed fingers) and have orders to fill (YEAH!), hucksterish advertisements to post, websites to update, emails to answer and grandchildren to spend time with. I'll also get to lead a field trip this Sunday, and hunt for the wild Blue G, my favorite prey! :drool: Be sure to check our website for regular updates. I'm working today on more chiastolite photos and collecting tips, and hopefully getting some new listings up, too. Thanks! Kris
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Post by gingerkid on Dec 27, 2012 18:31:00 GMT -5
Hi, Kris! Hope you feel much better asap so you can enjoy spending time with your grandkids!! Greatly appreciate your response and clarification on the name of the Blue G. Was just a bit confused on it's name after reading the gem ID report. :blush: Looking forward to seeing your chiastolite listings, too! Hope to purchase some also. :cheesy: Andalusite, which chiastolite is a variety, is one of the most beautiful gemstones to me.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Dec 27, 2012 19:26:36 GMT -5
Wow, Really enjoyed the chiastolite field trip report on your website. I used to collect the Mariposa County location on White Rock road a couple of times per year but most the crystals there are mere fragments and seldom over 1/2 -3/4 inch wide. Met a rancher out there one time who a said further down the road towards the valley there were really large crystals like 5" long by one inch thick but we drove up and down that road numerous times with absolutely no luck. I still have twenty pounds of crystals in jars out in the shop. Kind of funny but there are actually Japanese tour buses that visit the White Rock site sometimes as the Japanese apparently value those crystals as good luck stone. There's also a place for clear andalusite crystals in northern Mariposa county I visited a couple of times but despite reports of large crystals, those we found were only 1/8" or so across. Found nice pyrophyllite at that location too....Mel
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Post by gingerkid on Dec 27, 2012 20:48:16 GMT -5
Hi, Mel! Do you have any pics of the chiastolite you have stored in jars, and of the andalusite?
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Dec 27, 2012 21:00:26 GMT -5
gingerkid: I didn't collect any of the clear crystals because they were too small to do anything with. I'll take a photo of the chiastolite and post it here tomorrow. I occasionally tumble the crystal sections for the kids who are intrigued by the "cross rocks"...Mel
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Post by gingerkid on Dec 27, 2012 21:10:06 GMT -5
Thank you, Mel!! Agree with the kids, chiastolite is fascinating!!
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Dec 28, 2012 10:09:08 GMT -5
Jan, Posted a chiastolite thread with a few pics in the members photograph section....Mel
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Post by gingerkid on Dec 28, 2012 11:29:40 GMT -5
Thanks, Mel, I found the thread earlier!! ( :drool: ) Hi, Kris, hope you are feeling much better, and sorry to bother you again, but wondered if the Blue G is "Lawsonite in feldspar granite?" :blush: Is the Lawsonite the blue material? :blush:
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Post by deb193redux on Dec 28, 2012 12:08:12 GMT -5
consensus is not a granite, as that is volcanic. since this is metamorphic, some other word meaning mix of materials.
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Post by gingerkid on Dec 29, 2012 12:29:14 GMT -5
Thank You, Daniel!
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metalsmith
Cave Dweller
Member since October 2012
Posts: 1,537
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Post by metalsmith on Dec 29, 2012 16:55:12 GMT -5
Blue-G appears to be a rock - which is a mix of minerals rather than a single MINERAL. It is thought to be metamorphic, which means that it has been (in common terminology) either cooked or stamped on - or a combination of both by the earth's heat and compressive forces. Cooking and pressure can cause fractionation. Fractionation is a bit like deriving gas from crude oil - heat it and some of it boils off. Not only that but the residual heat causes the remaining minerals to take on a particular compositional mixture. For example quick-setting molten chocolate on a marble slab ensures chocolate as the product, but leaving it in a warm room for a year or two ensures that the fats separate and leaves something pretty inedible. In geology, the opposite sentiment applies - the more fractionation the better. Pressure acts a bit like taking a piece of bread and then stamping on it. It changes the structure and then goes on to change the minerals, like taking carbon and changing it to diamond at a molecular level. And yeah, I know I'm mixing my metaphors here! BlueG appears to be a pretty spectacular ROCK, something along the lines of a Jadeite, but of different chemistry. IMHO it is a Blue-schist, but fractionated (as per the oil analogy). Blue-schist is a description of the level of cooking and pressure experienced by the rock and results in a characteristic 'flavour' which means that Lawsonite (and likely glaucophane) are produced (amongst others). However, again IMHO, it is not, as a rock, gem-grade. BTW as a geologist (I am not a GEMOLOGIST), hence I researched my definition of gem to a PHD qualified GEMOLOGIST: www.bwsmigel.info/Lessons1and2/DEBasicTerms.htmlI think some good value could be had from good quality blue, BlueG, remembering that it is a rare, semi-precious rock. Hope this is understandable (and not patronising) and useful.
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hand2mouthmining
spending too much on rocks
Purveyors of California Gem Rock
Member since September 2011
Posts: 495
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Post by hand2mouthmining on Dec 30, 2012 23:38:51 GMT -5
Blue-G appears to be a rock - which is a mix of minerals rather than a single MINERAL. It is thought to be metamorphic, which means that it has been (in common terminology) either cooked or stamped on - or a combination of both by the earth's heat and compressive forces. Cooking and pressure can cause fractionation. Fractionation is a bit like deriving gas from crude oil - heat it and some of it boils off. Not only that but the residual heat causes the remaining minerals to take on a particular compositional mixture. For example quick-setting molten chocolate on a marble slab ensures chocolate as the product, but leaving it in a warm room for a year or two ensures that the fats separate and leaves something pretty inedible. In geology, the opposite sentiment applies - the more fractionation the better. Pressure acts a bit like taking a piece of bread and then stamping on it. It changes the structure and then goes on to change the minerals, like taking carbon and changing it to diamond at a molecular level. And yeah, I know I'm mixing my metaphors here! BlueG appears to be a pretty spectacular ROCK, something along the lines of a Jadeite, but of different chemistry. IMHO it is a Blue-schist, but fractionated (as per the oil analogy). Blue-schist is a description of the level of cooking and pressure experienced by the rock and results in a characteristic 'flavour' which means that Lawsonite (and likely glaucophane) are produced (amongst others). However, again IMHO, it is not, as a rock, gem-grade. BTW as a geologist (I am not a GEMOLOGIST), hence I researched my definition of gem to a PHD qualified GEMOLOGIST: www.bwsmigel.info/Lessons1and2/DEBasicTerms.htmlI think some good value could be had from good quality blue, BlueG, remembering that it is a rare, semi-precious rock. Hope this is understandable (and not patronising) and useful. Thanks for the great explanations and analogies, Metalsmith. Fractionation and colloidal behavior would appear to have taken a large part in the creation of the nodular varieties of Blue G. Sincere thanks for lending your expertise to the topic. In practical terms, we still have to have a common trade name for various sources, and will use the term Gem Lawsonite to that aim. After all, Dictionary.com also cites the word "gem" as referring to a muffin! Perhaps, like "gembone", it will be accepted over time. Jan, I'm working on a question and answer article for Blue G, and will send you a PM. Regards, Kris
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Post by gingerkid on Dec 31, 2012 9:15:53 GMT -5
Happy New Year!! Hi, metalsmith, and thanks for your explanation. I think I follow what you're saying. ehem. :blush: Dr. Barbara Smigel gives an excellent free gemology course that you provided a link to give an explanation for the word "gem." She facets some beautiful stones, too, and hosted the acstones (Artistic Colored Stones) website until she retired. I used to ask her lots of questions on her website concerning gems. :blush: A lot of her material is on the International Gem Society's website also. Thanks, Kris!! Looking forward to reading the article!! Sorry for the 20 question ordeal. :blush:
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metalsmith
Cave Dweller
Member since October 2012
Posts: 1,537
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Post by metalsmith on Dec 31, 2012 10:22:21 GMT -5
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Post by gingerkid on Dec 31, 2012 10:33:31 GMT -5
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Post by Pat on Dec 31, 2012 10:41:32 GMT -5
metalsmith, that is funny!
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Geoff
spending too much on rocks
Please add 1074 to my post number.
Member since December 2012
Posts: 446
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Post by Geoff on Dec 31, 2012 17:22:13 GMT -5
Curious if any of you have seen this 1965 report titled: Petrogenesis of Franciscan glaucophane schists and associated metamorphic rocks, California
"Rocks of the glaucophane-schist facies are widely though irregularly developed in the Franciscan formation of California. Minerals critical of the facies are lawsonite, aragonite, jadeite and omphacitic pyroxenes associated with quartz; amphiboles of the glaucophane-crossite series are almost ubiquitous. The most widely distributed rock, occurring over areas of many square kilometers, is jadeite-lawsonite metagraywacke, commonly veined with aragonite. More spectacular, but occurring mainly in isolated blocks are coarse-grained glaucophane-lawsonite Schists of many kinds. Commonly, but by no means invariably, they are closely associated with bodies of serpentinite. Also common in the vicinity of serpentinite masses are blocks of amphibolite and eclogite. All the metamorphic rocks are considered to be Franciscan sediments and basic volcanics metamorphosed and metasomatized in the deep levels of a folded geosynclinal prism. Experimental data on the stability fields of jadeite-quartz, aragonite, and lawsonite show that the glaucophane-schist facies represents metamorphism at pressures of between 5 and 10 kb and temperatures of 150 300° C. Such conditions could develop at depths greater than 15 km provided a very low geothermal gradient (10°/km) were maintained. The metagray-wackes are considered to represent a regional response to such conditions. The role of serpentinites in glaucophane-schist metamorphism is discussed in terms of a tentatively proposed model: — In very deep levels — perhaps at depths as great as 30 km, bodies of hot ultramafic magma develop restricted aureoles' in which temperatures of 400 600° C are maintained fer perhaps 100 1000 years. The products of metamorphism, which also involves desilication under the influence of the ultramafic magma, are eclogite and amphibolite. Later, and perhaps at higher levels serpentinization of the now solid ultramafic masses (near 400° C), causes renewed metamorphism at lower grades. Marginal development of glaucophane Schists and prehnite and hydrogarnet rocks, and retrogressive alteration of eclogite and amphibolite to glaucophane-schist assemblages is attributed to this period."
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Post by Pat on Dec 31, 2012 18:30:26 GMT -5
Soooo, what's it say?
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Post by stoner on Dec 31, 2012 20:12:50 GMT -5
Welcome back Geoff, glad you came back.
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hand2mouthmining
spending too much on rocks
Purveyors of California Gem Rock
Member since September 2011
Posts: 495
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Post by hand2mouthmining on Jan 1, 2013 1:46:39 GMT -5
Curious if any of you have seen this 1965 report titled: Petrogenesis of Franciscan glaucophane schists and associated metamorphic rocks, California "Rocks of the glaucophane-schist facies are widely though irregularly developed in the Franciscan formation of California. Minerals critical of the facies are lawsonite, aragonite, jadeite and omphacitic pyroxenes associated with quartz; amphiboles of the glaucophane-crossite series are almost ubiquitous. The most widely distributed rock, occurring over areas of many square kilometers, is jadeite-lawsonite metagraywacke, commonly veined with aragonite. More spectacular, but occurring mainly in isolated blocks are coarse-grained glaucophane-lawsonite Schists of many kinds. Commonly, but by no means invariably, they are closely associated with bodies of serpentinite. Also common in the vicinity of serpentinite masses are blocks of amphibolite and eclogite. All the metamorphic rocks are considered to be Franciscan sediments and basic volcanics metamorphosed and metasomatized in the deep levels of a folded geosynclinal prism. Experimental data on the stability fields of jadeite-quartz, aragonite, and lawsonite show that the glaucophane-schist facies represents metamorphism at pressures of between 5 and 10 kb and temperatures of 150 300° C. Such conditions could develop at depths greater than 15 km provided a very low geothermal gradient (10°/km) were maintained. The metagray-wackes are considered to represent a regional response to such conditions. The role of serpentinites in glaucophane-schist metamorphism is discussed in terms of a tentatively proposed model: — In very deep levels — perhaps at depths as great as 30 km, bodies of hot ultramafic magma develop restricted aureoles' in which temperatures of 400 600° C are maintained fer perhaps 100 1000 years. The products of metamorphism, which also involves desilication under the influence of the ultramafic magma, are eclogite and amphibolite. Later, and perhaps at higher levels serpentinization of the now solid ultramafic masses (near 400° C), causes renewed metamorphism at lower grades. Marginal development of glaucophane Schists and prehnite and hydrogarnet rocks, and retrogressive alteration of eclogite and amphibolite to glaucophane-schist assemblages is attributed to this period." Geoff, thanks for posting that excerpt from the 1965 report. It's a great example of just how different a language petrology is. There are a good number of reports that note glaucophane-Lawsonite conglomerates, and sadly, most are pretty much beyond layman's level understanding. You posted one of the more straightforward passages; it only took me 3 readings to understand! Thanks for stretching my brain. More for you, Metalsmith: My current report searches are looking for primary Lawsonite conglomerate occurrences. So far, only one pertinent hit, a report on the Pacheco Pass/Diablo Range. I'll link when it's digested. We had a graduate geologist on yesterdays field trip, and spoke at length about the blue schist question. We found a number of blue schist specimens that made him very happy (he's a blue schist fanatic!) including a well silicified chunk of Navy blue with orange garnet, amphibole and mica. He went home happy. He agreed that Blue G might be closely related to our local blue schist, but had definite differences. The largest is the prevalence of Lawsonite as the blue colorant, as opposed to the Navy blue to almost black of the blue schist attributed to galucophane. He was quite happy to see the high silica blue schist of the Panoche Hills firsthand, and several rockhounds found marvelous well "agatized" lapidary worthy examples. He grinned at my use of that term, and conceded it would do, in layman's conversation. The geologist felt that my notion of repeated cycles of silicification through repeated subduction and upthrust, post-fractionation might have merit, explaining the unusually high silica blue schist as well as the Blue G. Feel free to mull it over and give me your thoughts. We'll cab and post some of the blue schist as soon as our current shop upgrades are finished. We'll keep digging, get more petrology done when possible, and keep inviting you guys down to visit us. There's plenty of rock to go around, so come on down! Happy New Year! Kris
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