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Sierra de la Cruz (Lake Jaco), Sierra Mojada Municipality, Coahuila, Mexicoi
Regional Level Types
Sierra de la Cruz (Lake Jaco)Sierra
Sierra Mojada MunicipalityMunicipality

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Latitude & Longitude:
27° North , 103° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
Locality type:


Most of the garnets attributed to Lake Jaco come from the Sierra de la Cruz, Mun. de Sierra Mojada, Coahuila, Mexico. No garnets come from Lake Jaco.

Back in the 1950s a well-known mineral dealer in Monrovia, California, George Burnham traveled to Mapimi, Mexico to collect minerals at that famous mine. The mine was owned by the big Mexican mining company of Peñoles. They had stopped working the mine and had made a deal with a collective of local miners and they were continuing to work the mine as best they could. George cut a deal with this "colectivo". He had cut a deal with the local mining collective to get permission to collect minerals in the mine. While he was there, his campsite was visited by a representative of Peñoles who asked him what he was doing there. Hostility was in the air till he explained that he had worked out a deal with the "colectivo" and was there to collect mineral specimens and answered all questions asked by the representative who also knew something about minerals and then they became friends and spent several hours talking about minerals. The man asked George if he had ever seen any pink garnets and George said no he had not and the man told him about another Peñoles property where he could get some. George arranged at a later date to visit the mine and take a look at the pink garnets. Some months later when he got to the mine on a subsequent trip to Mexico, he found the mine office indeed had some very interesting pink garnets, but they were not from the mine, but rather from the hacienda belonging to a relative of one of the mine's employees. They made immediate arrangements to visit the hacienda. The hacienda was in Coahuila state near the Sierra de la Cruz. They made arrangements to borrow horses and pack animals and went up into the mountains and found abundant specimens of pink and other colored garnets. While they were collecting there was some discussion about what locality they should give the garnets because since these pink garnets had never been seen before and they would be hot items, if they gave the exact locality many other people would descend on the spot and dilute the value of their find. Also, the man who owned the hacienda was not keen on having a lot of people bothering him about garnets. From the top of the mountain, George could look west into Chihuahua state to a big dry lake or at least dry some of the time. This was Lake Jaco. George labeled his specimens Lake Jaco, Mexico. This is where the locality name came from and it is still to be seen on the labels for many Mexican Garnet crystals, and it is an incorrect locality for the reasons stated above.
[Rock Currier 2010]

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

3 erroneous literature entries.

Detailed Mineral List:

Formula: Ca3Al2(SiO4)3
Reference: (See explanation in "locality" description.)
Grossular var: Rosolite
Formula: Ca3Al2(SiO4)3
Reference: (See explanation in "locality" description.)
Formula: (Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Reference: (See explanation in "locality" description.)

List of minerals arranged by Strunz 10th Edition classification

Group 9 - Silicates
Grossular ?9.AD.25Ca3Al2(SiO4)3
var: Rosolite ?9.AD.25Ca3Al2(SiO4)3
Vesuvianite ?9.BG.35(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10

List of minerals arranged by Dana 8th Edition classification

Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with cations in [6] and >[6] coordination
Grossular ?51.4.3b.2Ca3Al2(SiO4)3
Group 58 - SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [6] and higher coordination; single and double groups (n = 1, 2)
Vesuvianite ?,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Unclassified Minerals, Mixtures, etc.
var: Rosolite ?

List of minerals for each chemical element

H Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
B Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
O GrossularCa3Al2(SiO4)3
O Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
O Grossular (var: Rosolite)Ca3Al2(SiO4)3
F Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Na Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Mg Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Al GrossularCa3Al2(SiO4)3
Al Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Al Grossular (var: Rosolite)Ca3Al2(SiO4)3
Si GrossularCa3Al2(SiO4)3
Si Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Si Grossular (var: Rosolite)Ca3Al2(SiO4)3
Ca GrossularCa3Al2(SiO4)3
Ca Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Ca Grossular (var: Rosolite)Ca3Al2(SiO4)3
Fe Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10


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The above information was obtained from George Burnham during a series of conversations about his early days in business and his well-known trip around the world in the early 50s with Jack Jago shortly before his death.
[Rock Currier 2010]

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