What it is

RockTumbler.com is an online and mail-order supplier of rock tumblers, tumbling supplies and tumbling rough based in Lemont Furnace, Pennsylvania, with its own store and shopping cart. Its About page says owner Hobart King is a retired geologist with a Ph.D. in geology and a GIA Graduate Gemologist diploma who writes the rock, mineral and gem articles on Geology.com, and that the site is “a family business operated by his children and grandchildren.” The site says, “Before we sell anything as ‘tumbling rough’ we tumble a few batches ourselves,” and publishes a rotary and a vibratory recipe for each rough it sells.

Who it’s for

Beginning and experienced rock tumblers in the United States who want tumblers, grit, polish, media and tested rough from one store, with detailed instructions.

Why it’s listed

It’s the business’s own store, with product pages that show prices and add-to-cart buttons and a working shopping cart on its own secure.rocktumbler.com domain (orders are processed by GeoShops.com, LLC). It is not a marketplace, not Amazon and not an affiliate storefront.

Official URL

https://rocktumbler.com/

Cart: https://secure.rocktumbler.com/cgi-bin/UCEditor?MERCHANTID=MAPS&ThemeCode=RT

Example product (tumbler): https://rocktumbler.com/thumlers/model-ar-2.shtml

Example product (grit): https://rocktumbler.com/grit.shtml

Example product (rough): https://rocktumbler.com/rough/dragon-blood/

All tumbling rough: https://rocktumbler.com/rough/

About: https://rocktumbler.com/about-us.shtml

Ordering, shipping and returns: https://rocktumbler.com/faq.shtml

(First-party store checked 2026-10-20. Every cited URL returned HTTP 200 to curl with a Chrome user agent.)

Location

GeoShops.com, 1040 Eberly Way, Suite 150, Lemont Furnace, PA 15456 (the mail-order address). The site says all sales are online and by mail and that there is no walk-in store and no visits to the office.

This is a supplier with its own online store. It is not a club and not a school.

Notes

Prices on the check date (product pages): Thumler’s A-R2 two-barrel rotary tumbler $209.99 (tumbler only) or $269.99 as a kit with supplies; coarse 60/90 silicon carbide grit $6.99 a pound, $26.99 for 5 pounds, $48.99 for 10 pounds and $89.99 for 20 pounds; Dragon Blood tumbling rough $11.99 for one pound or $23.99 for two (refill kit $36.99); SuperMix bulk rough $39.99 for 5 pounds.
Range: Thumler’s rotary tumblers (MP-1, A-R1, A-R2, A-R12, Model B), Thumler’s UV-10 and UV-18 and Lot-O vibratory tumblers, tumbler parts, grit, polish, ceramic media, refill kits, tumbling rough, tumbled stones and books.
Scope: this is a rock-tumbling store. It does not sell slab saws, cabbing machines or saw blades.
Shipping: United States addresses only (including U.S. territories and APO/FPO/DPO). No shipping to Canada or other countries. Orders usually ship the same or next business day by USPS or FedEx.
Returns: unopened, unused items within 30 days. Opened grit, polish, rough and tumbled stones cannot be returned. The buyer pays return shipping. Holiday gifts bought November 1–December 25 can be returned until January 31.
Payment: Visa and Mastercard online, or check or money order by mail. No purchase orders.
Photo: a first-party photo of the store’s test tumblers from the About page (tumblers-we-are-running.jpg, 620 × 260). The site logo (logo.jpg, 527 × 85) is under the 100 px minimum and the site sets no og:image, so the photo is used instead.
Pennsylvania has earlier listings (Bey’s Rock Shop, GoggleWorks and Tuscarora Lapidary Society). This is the state’s second supplier.
Not affiliated with Lapidary Plaza. No purchase, account or contact form was used.

FAQ

Q: What does RockTumbler.com sell?
A: Rock tumblers (Thumler’s rotary and vibratory, Lot-O), tumbler parts, silicon carbide grit, polish, ceramic media, refill kits, tested tumbling rough, tumbled stones and books.

Q: Can I order online?
A: Yes, through the store’s own shopping cart. You can also order by mail with a check or money order.

Q: Is the tumbling rough tested?
A: Yes. The site says staff tumble every rough before selling it and publish rotary and vibratory recipes on each rough’s page.

Q: Can I visit the store?
A: No. Sales are online and by mail only. There is no walk-in store.

Q: Does it ship outside the United States?
A: No. It ships only to U.S. addresses, including territories and military addresses.